m

VZA

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SMITHSONIAN INSTITUTION LIBRARIES

DRAPER FAMILY COLLECTION

GIFT OF

DANIEL C. DRAPER

-

e,

u'" *■ ^4 U/iet.

A SUPPLEMENT

TO

TJKE'S DICTIONARY

OF

ARTS, MANUFACTURES, AND MINE

CONTAINING

A CLEAR EXPOSITION OF THEIR PRINCIPLES AND PRACTICE.

FEOM THE LAST EDITION,

EDITED BY EGBERT HUNT, F.R.S., F.S.S.,

Keeper of Mining Records, Formerly Professor of Physics, Government School of Mines, &c, &c,

ASSISTED BY NUMEROUS CONTRIBUTORS EMINENT IN SCIENCE AND FAMILIAR "WITH

MANUFACTURES.

ILLUSTRATED WITH SEVEN HUNDRED ENGRAVINGS ON "WOOD.

NEW YORK: APPLETQN AND COMPANY,

443 AND 445 BROADWAY. 1868/

This Volume of Ure's	2 Dictionary of Arts,. Manufactures, and
Mines, contains the additional knowledge which has accumulated
within the past ten years.	Not a	year has passed but that some
important improvements in the Arts and Sciences have taken place,
all of which form an important	increase to knowledge, which
cannot well be dispensed	with by	those who are engaged in the
various pursuits in which	they are	employed.
The following are a few, amor	g the many, who are specially
Interested, viz. :
Artisans,		Gunsmiths,
Assayers,		Gas Light Companies,
Brewers,		Glass Makers,
Bakers,		Hat Makers,
Boiler Makers,		Iron Mongers,
Brass Founders,		India Rubber Manufacturers,
Bleachers,		Ink Manufacturers,
Brick Makers,		Leather Dealei's,
Button Manufacturers,		Miners,
Chemists,		Manufacturers,
Coal Dealers,	■	Plumbers,
Calico Printers,		Paper Manufacturers,
Candle Makers,		Photographers,
Confectioners,		Painters,
Coppersmiths,		Perfumers,
Cotton Factories,		Pyrotechnists,
Carriage Makers,		Pope Makers,
Distillers,		Shipping Merchants,
Dyers,		Sugar Refiners,
Druggists,		Silversmiths,
Engineers,		Soap Makers,
Farmers,		Tanners,
Furriers,		Tobacconists,
Founders,		Weavers,
Gold Beaters,		Wine Growers,
&c,	&c..	&c.

PREFACE.

Ure's Dictionary of Arts, Manufactures, and Mines has long had the reputation of a standard authority upon the subjects of which it treats. But such is the inventive activity of the age, and the rapid improvement in art processes, that a work of this kind can only maintain its character by frequent and extensive additions. While the distinguished author was in the vigor of his intellect, the revisions of the work kept pace with the progress of improvement, but at his demise it was found necessary to organize a plan for bringing up the Dictionary to the present state of knowledge. Accordingly, Mr. Robert Hunt, a gentleman whose high scientific position gave warrant that the work would be well performed, assumed the editorship, and a corps of the ablest practical and scientific men in England was secured to prepare articles in their several depart- ments. The following remarks, condensed from the preface to the Eng- lish edition, will explain the purpose and plan of the editor.

" The objects which have been steadily kept in view are the follow- ing : To furnish a work of reference on all points connected with the sub- jects included in its design, which should be of the most reliable character. To give to the scientific student and the public the most exact details of those manufactures which involve the application of the discoveries of either physics or chemistry. To include so much of science as may render the philosophy of manufactures at once intelligible, and enable the technical man to appreciate the value of abstruse research.

" I commenced the new edition of Ure's Dictionary with an earnest determination to render the work as complete and as correct as it was possible for me to make it. In my necessities I have asked the aid of the manufacturer, and the advice of the man of science, and never having been refused the aid solicited, I am led to hope that those who may pos- sess these volumes will find in them more practical knowledge than ex- ists in any work of a similar character."

This volume of Ure's Dictionary contains the chief additions made to the late English edition. Those portions of the work which concerned mainly the English, their commercial and manufacturing resources and statistics, the least important historic notices, and some definitions in pure science, which seemed hardly embraced within the defined scope of the work, have been omitted. By this means the original and valuable contributions to the work have been brought within the limits of a single

4 PREFACE.

volume, which has lost nothing of its real value. This supplementary volume is rich with the latest results of inquiry, containing all the new and important matter and illustrations of the three English volumes costing $38, while the complete American edition of the work, in three volumes, comprising 3212 pages, with 2300 engravings, forms the com- pletest repertory of arts, manufactures, and mines, which has been yet published.

Subjoined is a list of the contributors, whose initials will be found appended to their respective articles. Mr. Hunt avows the authorship of the rest.

G. ANSELL, Esq., Royal Mint.

H. K. BAMBER, Esq., F.C.S.,, &c.

JE. W. BINNEY, Esq., F.G.S., &c, Manchester.

H. W. BONE, Esq. Euameller.

'HENRY W. BRISTOW, Esq., F.G.S. Geo- logical Survey of Great Britain.

R. J. COURTNEY, Esq. Superintendent of Messrs. Spottiswoode and Co.'s Printing office.

JAMES DAFFORNE, Esq. Assistant Editor of the Art Journal.

JOHN DARLINGTON, Esq.- Mining Engi- neer. Author of Miner's Handbook.

F. W. FAIRHOLT, Esq., F.R.A.S. Author of Costume in England, Dictionary of Terms in Art, &c.

E. FRANKLAND, Esq., Ph.D., F.R.S., and C.S. Professor of Chemistry at St. Bartholo- mew's Hospital, and Lecturer on Chemistry at the Eoyal Indian Military College, Addiscombe.

ALFRED FRYER, Esq. Sugar Refiner, Man- chester.

{The late) T. H. HENRY, Esq., F.R.S. and

C.S.

R. HERRING, Esq. Author of History of

Paper Manufacture. JAMES HIGGINS, Esq. Calico Printer, &c,

Manchester. W. HERAPATH, Esq., M.D., &c. SAMUEL HOCKING, Esq., C.E., Seville. RICHARD W. HUNT, Esq. Brewer, Leeds. T. B. JORDAN, Esq. Engineer, Inventor of

Wood Carving Machinery. WILLIAM LINTON, Esq. Artist, Author of

Ancient and Modern Colors.

JAMES McADAM, Jun., Esq. Secretary of the Eoyal Society for the Cultivation of Flax in Ireland.

{The late) HERBERT MACKWORTH, Esq., C.E., F.O.S. One of H. M Inspectors of Coal Miners.

HENRY MARLES, Esq., L.R.C.P. Author of English Grammar, Currying and Leather.

DAVID MORRIS, Esq., of Manchester. Au- thor of Cottonopolis, &c.

JAMES NAPIER, Esq., .F.C.S. Author of Manual of Dyeing, Electro-Metallurgy, An- cient Works in Metal, &c.

D. NAPIER, Esq., C.E., &c.

A. NORMANDY, Esq., M.D., F.C.S. Author of Handbook of Commercial Chemistry.

HENRY M. NOAD, Esq., Ph.D., F.R.S. Au- thor of A Manual of Electricity, &.C.

AUGST. P. NORTHCOTE, Esq. F.C.S. As- sistant Chemist, University of Oxford.

ROBERT OXLAND, Esq., F.C.S. One of the

Authors of Metals and their Alloys.

THOMAS JOHN PEARSALL, Esq., F.C.S.

Secretary to London Mechanics' Institution. SEPTIMUS PIESSE, Esq. Author of Treatise

on Art of Perfumery, &c. JOHN ARTHUR PHILLIPS, Esq. Graduate

of the Imperial School of Mines, Paris, Author

of Manual of Metallurgy.

ANDREW CROMBIE RAMSAY, Esq., F.R.S. and G.S., Professor of Geology, Government School of Mines, Local Director of the Geologi- cal Survey of Great Britain.

EBENEZER ROGERS, C.E., F.G.S. Late President of the South Wales Institute of En- gineers.

CHARLES SANDERSON, Esq., Sheffield. Author of Papers on Stetl and Iron.

E. SCHUNCK, Esq., Ph.D., F.R.S., and C.S.

R. ANGUS SMITH, Esq., Ph.D., F.R.S. Au- thor of various Papers on Air and Water, Life of Dalton, and llistory of Atomic Theory, &c.

WARINGTON W. SMYTH, Esq., M.A., F.R.S. and G. S. Professor of Mining and Mineraloey, Government School of Mines, and Inspector of Crown Mines.

THOMAS SOPWITH, Esq., C.E., F.R.S., and G.S. Author of Lsometrical Drawing, &c.

ROBERT DUNDAS THOMSON, Esq., M.D., F.E.S. Professor of Chemistry in St. Thomas's Hospital College.

ALFRED TYLOR, Esq., F.G.S. Author of Treatise on Metal Work.

A. VOELCKER, Esq., Ph.D., F.C.S. Profes- sor of Chemistry, Agricultural College, Ciren- cester, and Consulting Chemist to the Eoyal Agricultural Society of England.

CHARLES V. WALKER, Esq., F.R.S., F.E.A.S. Engineer of Telegraphs and Time to the South Eastern Eaihvay Company, Author of Electrotype Manipulation, Translator of Kcemts' Meteorology, Dela Rive's Electricity,

■ &c.

C. GREVILLE WILLIAMS, Esq. Author of A Handbook of Chemical Manipulation, &c.

{The late) HENRY M. WITT, Esq., F.C.S. Assistant Chemist, Government School of Mines.

With special assistance and information from the late Sir Wm. Reid, C.B., Governor of Malta ; Sir Wm. Armstrong, C.E., &c. ; Robert Mallet, Esq., C.E., F R.S., &c. ; Captain Drayson, Royal Artillery ; George W. Lenox, Esq. ; and many others-

SUPPLEMENT

DICTIONARY OF ARTS, MANUFACTURES, AND MINES.

ABA. A woollen stuff manufactured in Turkey.

ABACA. A species of fibre obtained in the Philippine Islands in abundance. Some authorities refer those fibres to the palm-tree known as the Abaca, or Anisa textilis. There seem, indeed, several well-known varieties of fibre under this name, some so fine that they are used in the most delicate and costly textures, mixed with fibres of the pine-apple, form- ing Pina muslins and textures equal to the best muslins of Bengal. Of the coarser fibres, mats, cordage, and sail-cloth are made. M. Duchesne states, that the well-known fibrous manufactures of Manilla have led to the manufacture of the fibres themselves, at Paris, into many articles of furniture and dress. Their brilliancy and strength give remarkable fitness for bonnets, tapestry, carpets, network, hammocks, &c. The only manufactured articles exported from the Philippine Islands, enumerated by Thomas de Comyn, Madrid, 1820 (transl. by Walton), besides a few tanned buffalo hides and skins, are 8,000 to 12,000 pieces of light sail-cloth, and 200,000 lbs. of assorted abaca cordage.

ABIES (in Botany), the fir, a genus of trees which belong to the coniferous tribe. These trees are well known from their ornamental character, and for the valuable timber which they produce. They yield several resins or gum resins, which are useful in the arts.

ABIES BALSAMEA (the Balm of Gilead fir) produces the Canadian balsam. This tree grows most abundantly in the colder regions of North America.

ABIES CANADENSIS (the hemlock spruce fir). A considerable quantity of the es- sence of spruce is extracted from the shoots of this tree ; it is, however, also obtained from other varieties of the spruce fir.

ABIES PICE A of Linnaeus (Abies pectinata of De Candole). The Silver fir, producing the Burgundy pitch and the Strasburg turpentine.

ABLETTE, or ABLE, is a name given to several species of fish, but particularly to the Bleak, the scales of which are employed for making the pearl essence which is used in the manufacture of artificial pearls. See Pearls, Artificial.

ABRASION. The figuration of materials by wearing down the surface. See ' File, vol. i.

ACACIA. (L. acacia, a thorn; Gr. aid), a point.) The acacia is a very extensive genus of trees or shrubby plants, inhabiting the tropical regions generally, but extending in some few instances into the temperate zone ; being found, for example, in Australia, and the neighboring islands. Botanists are acquainted with nearly 300 species of the acacia ; some of these yield the gum arabic and the gum catechu of commerce ; while the bark of others yields a large quantity of tannin, especially a variety which grows in Van Diemen's Land, or Tasmania. See Arabic, Gum ; Catechu.

ACACIA ARABICA. An inhabitant of Arabia, the East Indies, and Abyssinia. One of the plants yielding the gum arabic, which is procured by wounding the bark of the tree, after which the sap flows out and hardens in transparent lumps.

ACACIA CATECHU. The catechu acacia (Mimosa catechu of Linnaeus) is a tree with a moderately high and stout stem, growing in mountainous places in Bengal and Coromandel, and in other parts of Asia. Its unripe pods and wood, by decoction, yield the catechu or terra Japonica of the shops.

ACESCENT. Substances which have a tendency to pass into an acid state ; as an infu- sion of malt, &c.

6 AOETAL.

ACETAL. (C12 H" O4.) One of the products of the oxidation of alcohol under tho in- fluence of the oxygen condensed in platina black. It is a colorless, mobile, ethereal liquid boiling at 221° F. Its density in the fluid state is 0-821 at 72°. The specific gravity of its vapor 4-13S Stas. (mean of three experiments) : calculation gives 4-083 for four volumes of vapor. — For the description of the modes of determining vapor volume, consult some standard chemical work. — The recent researches of Wurtz render it evident that the con- stitution of acetal is quite different to what has generally been supposed, and that it is in fact glycodiethyline ; that is to say, glycole in which two equivalents of hydrogen are re- placed by two equivalents of ethyle. — C. G. W.

ACETATE. (Ackate, Ft. ; Essigsaure, Germ.) Any salient compound in which the acid constituent is acetic acid. All acetates are soluble in water : the least soluble being the acetates of tungsten, molybdenum, silver, and mercury. The acetates, especially those of lead and alumina, are of great importance to the arts. The acetates are all described un- der their respective bases ; — a rule which will be adopted with all the acids.

ACETIC ACID. (Acide acetigue, Ft. ; Essigsaure, Germ. ; Acidum aceticurn, Lat. ; Msel, Sax.) The word "acetic" is derived from the Latin acetum, applied to vinegar; probably the earliest known body possessing the sour taste and other properties which characterize acids ; hence the term Acid, "now become generic ; both the Latin word, and also the Saxon acid being from the root acics (Greek d/cJ;), an edge or point, in reference to the sharpness of the taste.

Acetic acid is produced either by the oxidation, or the destructive distillation, of organic bodies containing its elements — carbon, hydrogen, and oxygen.

The oxidation of organic bodies, in order to convert them into acetic acid, may be effected either : — 1, by exposing them in a finely divided state to the action of air or oxygen gas ; 2, by submitting them to the action of ferments, in the presence of a free supply of atmospheric air ; or, 3, by the action of chemical oxidizing agents.

When acetic acid is procured by the oxidation of organic bodies, it is generally alcohol that is employed ; but by whatever process alcohol is transformed into acetic acid, it is always first converted into an intermediate compound, aldehyde ; and this being a very vola- tile body, it is desirable always to effect the oxidation as completely and rapidly as possible, to avoid the loss of alcohol by the evaporation of this aldehyde.

Alcohol contains C4 H6 O2 Aldehyde " C4 H4 02 Acetic acid " C4 H4 O4

The process, therefore, consists first in the removal of two equivalents of hydrogen from alcohol, which are converted into water, — aldehyde being produced, — and then the further union of this aldehyde with two equivalents of oxygen to convert it into acetic acid. See Aldehyde.

By the oxidation of alcohol, pure acetic acid is obtained : but the vinegars of commerce are mixtures of the pure acetic acid with water ; with saccharine, gummy, and coloring mat- ters ; with certain ethers (especially the acetic ether), upon which their agreeable aromatic flavor depends ; with empyf eumatic oils, &c.

The pure acetic acid (free from water and other impurities) may be obtained most ad- vantageously, according to Melsens*, by distilling pure acetate of potash with an excess of acetic acid (which has been obtained by the redistillation of ordinary acetic acid, procured either by oxidizing alcohol, or by the destructive distillation of wood) : the acid which first passes over contains water ; but finally it is obtained free.

Properties of pure Acetic Acid. — When absolutely pure, acetic acid is a colorless liquid of specific gravity 1-064, which at temperatures below 62° F. (11° C.) solidifies into a color- less crystalline mass. It has strongly acid properties, being as powerfully corrosive as many mineral acids, causing vesication when applied to the skin ; and it possesses a peculiarly pungent, though not a disagreeable smell.

The vapor of the boiling acid is highly combustible, and burns with a blue flame. Hy- drated acetic acid dissolves camphor, gliadine, resins, the fibrine of blood, and several or- ganic compounds. When its vapor is conducted through a slightly ignited porcelain tube, it is converted entirely into carbonic acid and acetone, an atom of the acid being resolved into an atom of each of the resultants. At a white heat the acid vapor is converted into carbonic acid, carburetted hydrogen, and water.

It attracts water with great avidity, mixing with it in all proportions. Its solution in water increases in density with the increase of acetic acid up to a certain point ; but beyond this point its density again diminishes. Its maximum density being 1-073, and correspond- ing to an acid containing C4 H4 O4 -4- 2Aq., which may be extemporaneously produced by mixing 7V-2 parts of crytallized acetic acid with 22-8 parts of water. This hydrate boils at 104° C. (219° F.), whilst the crystallized acid boils only at 120° C. (248° F.)f

* Comptes rendns, six. 611. t Gerhardt, Chimie Organique, i. 71S.

ACETIC ACID. 7

The proportion of acetic acid in aqueous mixtures may therefore be ascertained, within certain limits, by determination of the specific gravity. See Acetimetry.

The following table, by Mohr, indicates the percentage of acetic acid in mixtures- of different specific gravities ; but of course this is only applicable in cases where no sugar or other bodies are present, which increase the specific gravity.

Abstract of Mohr s Table of the Specific Gravity of Mixtures of Acetic	Acid and Water.*
Percentage of Acetic Acid, t* H-i OK	Density.	Percentase of Acetic Acid, C* H< O*.	Density.
100	1-0635	45		1-055
95	1-070	40		1-051
90	1-073	35		1-046
85	1-073	30		1-040
80	1-0735	25		1-034
75	1-072	20		1-027
70	1-070	15		1-022
65	1-068	10		1-015
60	1-067	5		1-0067
55	1-064	1		1-001
50	1-060

Which numbers closely agree with those obtained by Dr. Ure. See vol. i. p. 5.

Acetic acid was formerly (and is still by some chemists) viewed as the hydrated teroxide of a radical acetyl, now called vinyl. See Chemical Formula.

(C4 H3) O3, HO

Acetyl.

And therefore an anhydrous acetic acid, C H3 03, is supposed to exist. Many attempts have been made to isolate this anhydrous acetic acid C4 H3 O3 ; and a body which has re- ceived this name has been quite recently obtained by Gerhardtf, by the double decomposi- tion of chloride of acetyl and an alkaline acetate, thus : —

C4 H3 (O2 CI) -f- KO,C4 H3 O3 = C8HG06 + K CI

Chloride of Acetate of (So-called) Chloride of

acetyl. potash. Anhydrous potassium.

acetic acid.

This body Gerhardt describes as a colorless liquid having a strong smell of acetic acid, but associated with the flavor of hawthorne blossom, having a specific gravity of 1-073, and boiling at 137° C. (278° F.) ; falling in water in the form of oily drops, only dissolving on gently heating that fluid. It is, however, not anhydrous acetic acid, but a compound iso- meric with the hypothetical anhydrous acetic acid C4 H3 O3, containing, in fact, double the amount of matter, its formula being C8 H6 O6.

The impure varieties of acetic acid known as vinegar, pyroligneous acid, &c, are the products met with in commerce, and therefore those require more minute description in this work.

Before describing the manufacture of these commercial articles, it may be interesting to allude to a method of oxidizing alcohol by means of spongy platinum ; which may yet meet with extensive practical application. It is a well-known fact that spongy platinum (e. g. platinum black), from its minute state of division, condenses the oxygen of the air within its pores ; consequently, when the vapor of alcohol comes in contact with this body, a supply of oxygen in a concentrated state is presented to it, and the platinum, without losing any of its properties, eifects the combination between the oxygen and the alcohol, converting the latter into acetic acid.

This may be illustrated by a very simple experiment. Place recently ignited spongy platinum, loosely distributed on a platinum-gauze, at a short distance over a saucer contain- ing warm alcohol, the whole standing under a bell-glass supported by wedges on a glass dish, so that, on removing the stopper from the bell-glass, a slow current of air circulates through the apparatus ; the spongy platinum soon begins to glow, in consequence of the combustion going on upon its surface, and acetic acid vapors are abundantly produced, which

* Mohr, Ann. der Chem. und Phar. xxxi. 227.

t Comptes rendus, xxxiv. 755.

8 ACETIC ACID,

condense and run down the sides of the glass. The simultaneous formation of aldehyde is at the same time, abundantly proved by its peculiar odor.

In Germany this method has been actually carried out on the large scale, and, if it -were not for the high price of platinum, and the heavy duty on alcohol, it might be extensively employed in this country, on account of its elegance and extreme simplicity.

Manufacture of Vinegar by Acetous Fermentation. — All liquids which are susceptible of the vinous fermentation are capable of yielding vinegar. A solution of suo-ar is the essential ingredient, which is converted first into alcohol, and subsequently into acetic acid. The liquids employed vary according to circumstances. In this country the vine- gar of commerce is obtained from an infusion of malt, and in wine countries from inferior wines.

The oxidation of alcohol is remarkably facilitated by the presence of nitrogenized organic bodies in a state of change, called ferments, hence the process is frequently termed acetous fermentation. Now, although in most cases the presence of these ferments curi- ously promotes the process, yet they have no specific action of this kind ; for we have already seen that, by exposure to air in a condensed state, alocohol, even when pure, is converted into acetic acid; and, moreover, the action of oxidizing agents, such as chromic and nitric acid, &c, is capable of effecting this change.

However, in the presence of a ferment, with a free supply of air, and at a temperature of from 60° to 90° F., alcohol is abundantly converted into acetic acid.

At the same time that the alcohol is converted # into acetic acid, the nitrogenized and other organic matters undergo peculiar changes, and often a white gelatinous mass is de- posited,— which contains Vibriones and other of the lower forms of organized beings, — and which has received the name of mother of vinegar,* from the supposition that the for- mation and development of this body, instead of being a secondary result of the process, was really its exciting cause.

Wine vinegar is of two kinds, white and red, according as it is prepared from white or red wine. White wine vinegar is usually preferred, and that made at Orleans is regarded as the best. Dr. Ure found its average specific gravity to be 1-019, and to contain from 64- to 7 per cent, of real acid ; according to the Edinburgh Pharmacopoeia, its specific gravity varies from 1-014 to 1-022.

1. Malt Vinegar. (British Vinegar; in Germany called Malz-Gctreide or Bier- essig.) In England vinegar is chiefly made from an infusion of malt, by first exciting in it the alcoholic fermentation, and subsequently inducing the oxidation of the alcohol into acetic acid.

The transformation of the fermented wort into vinegar was formerly effected in two ways, which were entirely opposite in their manner of operation. In one case the casks containing the fermented malt infusion (or gyle) were placed in close rooms, maintained at a uniform temperature ; in the other, they were arranged in rows in an open field, where they remained many months. As regards the convenience and interests of the manufac- turer, it appears that each method had its respective advantages, but both are now almost entirely abandoned for the more modern processes to be described — a short notice of the fielding process is, however, retained.

When fielding is resorted to, it must be commenced in the spring months, and then left to complete itself during the warm season. The fielding method requires a much larger extent of space and utensils than the stoving process. The casks are placed in several parallel tiers, with their bung side upwards and left open. Beneath some of the paths which separate the rows of casks are pipes communicating with the " back " at the top of the brewhouse ; and in the centre of each is a valve, opening into a concealed pipe. When the casks are about to be filled, a flexible hose is screwed on to this opening, the other end being inserted into the bung-hole of the cask, and the liquor in the "gyle back" at the brewhouse, by its hydrostatic pressure, flows through the underlying pipe and hose into the cask. The hose is so long as to admit of reaching all the casks in the same row, and is guided by a workman.

After some months the vinegar is made, and is drawn off by the following operation : — A long trough or sluice is laid by the side of one of the rows of casks, into which the vinegar is transferred by means of a syphon, whose shorter limb is inserted into the bung- hole of the cask. The trough inclines a little from one end to the other, and its lower end rests on a kind of travelling tank or cistern, wherein the vinegar from several casks is col- lected. A hose descends from the tank to the open valve of an underground pipe, which terminates in one of the buildings or stores, and, by the agency of a steam boiler and machinery, the pipe is exhausted of its air, and this causes the vinegar to flow through the hose into the valve of the pipe, and thence into the factory buildings. By this arrange- ment the whole of the vinegar is speedily drawn off. From the storehouse, where the vinegar is received, it is pumped into the refining or rape vessels.

* This substance has been supposed by some to be a fungus, and has been described by Mulder under the name of Mycooederni Aceti.

ACETIC ACID.

These rape vessels are generally filled with the stalks and skins of grapes or raisins, (the refuse of the British wine manufacturer is generally used,) and the liquor being admitted at the top, is allowed slowly to filter through them ; after passing through, it is pumped up again to the top, and this process is repeated until the acetification is complete. Sometimes wood shavings, straw, or spent tan, are substituted for the grape refuse, but the latter is generally preferred.

By this process, not only is the oxidation of the alcohol completed, but coagulable nitro- genous and mucilaginous matter is separated, and thus the vinegar rendered bright. It is finally pumped into store vats, where it is kept until put into casks for sale.

2. Sugar, Cider, Fruit, and Beet Vinegars. An excellent vinegar may be made for domestic purposes by adding, to a syrup consisting of one pound and a quarter of sugar for every gallon of water, a quarter of a pint of good yeast. The liquor being maintained at a heat of from 75° to 80° F., acetification will proceed so well that in 2 or 3 days it may be racked off from the sediment into the ripening cask, where it is to be mixed with 1 oz. of cream of tartar and 1 oz. of crushed raisins. When completely freed from the sweet taste, it should be drawn off clear into bottles, and closely corked up. The juices of cur- rants, gooseberries, and many other indigenous fruits, may be acetified either alone or in combination with syrup. • Vinegar made by the above process from sugar should have fully the Revenue strength. It will keep much better than malt vinegar, on account of the absence of gluten, and at the present low price of sugar will not cost more, when fined upon beech chips, than Is. per gallon.

The sugar solution may likewise be replaced by honey, cider, or any other alcoholic or saccharine liquid. An endless number of prescriptions exist, of which the following example may suffice : — 100 parts of water to 18 of brandy, 4 of honey, and 1 of tartar.

Messrs. Neale and Duyck, of London, patented a process, in 1841, for the manufacture of vinegar from beet-root.

The saccharine juice is pressed out of the beet, previously rasped to a pulp, then mixed with water and boiled ; this solution is fermented with yeast, and finally acetified in the usual way, the process being accelerated by blowing air up through the liquid, which is placed in a cylindrical vessel with fine holes at the bottom.

In some factories large quantities of sour ale and beer are converted into vinegar ; but it is usually of an inferior quality, in consequence of being liable to further fermentation.

Dr. Stenhouse has shown that when sea-weed is subjected to fermentation at a tempera- ture of 96° F., in the presence of lime, acetate of lime is formed, from which acetic acid may be liberated by the processes described under the head of Pyroligneous Acid. Although such large quantities of sea-weed are found on all our coasts, it does not yet appear that they have yet been utilized in this way, although they would still be, to a certain extent, valuable as manure after having been subjected to this process.

3. The German or Quick- Vinegar Process. (Schnellessigbereitung.) — In the manu- facture of vinegar it is highly important that as free a supply of air should be admitted to the liquid as possible, since, if the oxidation take place but slowly, a considerable loss may be sustained, from much of the alcohol, instead of being completely oxidized to acetic acid, being only converted into aldehyde, which, on account of its volatility, passes off in the state of vapor. This is secured in the German process by greatly enlarging the surface exposed to the air ; which, however, not only diminishes or prevents the formation of alde- hyde, but also greatly curtails the time necessary for the whole process. In fact, when this method was first introduced, from the supply of air being insufficient, very great loss was sustained from this cause, which was, however, easily remedied by increasing the number of air-holes in the apparatus.

This quick-vinegar process consists in passing the fermented liquor (which generally contains about 50 gallons of brandy of 60 per cent., and 37 gallons of beer or maltwort, with j-gftj; of ferment) two or three times through an apparatus called the Vinegar Genera- tor (essigbilder). See Graduator, vol. i.

The analogy between acetification and ordinary processes of decay, and even combustion, is well seen in this process -, for, as the oxidation proceeds, the temperature of the liquid rises to 100° or even 104° F. ; but if the temperature generated by the process itself be not sufficient, the temperature of the room in which the tuns are placed should be artifi- cially raised.

By this method 150 gallons of vinegar can be manufactured daily in ten tuns, which one man can superintend ; and the vinegar, in purity and clearness, resembles distilled vinegar.

It is better to avoid using liquors containing much suspended mucilaginous matter, which, collecting on the chips, quickly chokes up the apparatus, and not only impedes the process, but contaminates the product.

The chips and shavings may with advantage be replaced by charcoal in fragments, which, by the oxygen it contains condensed in its pores, still further accelerates the process. The charcoal would, of course, require re-igniting from time to time.

By destructive Distillation of Wood. Pyroligneous Acid. — The general nature of the

10

ACETIC ACID.

process of destructive distillation will be found detailed under the head of Distillation, Destructive ; as well as a list of products of the rearrangement of the molecules of organic bodies under the influence of heat in closed vessels. We shall, therefore, at once proceed to the details of the process as specially applied in the manufacture of acetic acid from wood. The forms of apparatus very generally employed on the continent for obtaining at the same time crude acetic acid, charcoal, and tar, are those of Schwartz and Reichenbach ; but in France the process is carried out with special reference to the production of acetic acid alone. Since the carbonizers of Reichenbach and Schwartz are employed with special reference to the manufacture of wood charcoal, the condensation of the volatile products being only a secondary consideration, they will be more appropriately described under the head of Charcoal.

In England the distillation is generally carried out in large iron retorts, placed horizon- tally in the furnace, the process, in fact, closely resembling the distillation of coal in the

manufacture of coal gas, 1 excepting that the retorts

are generally larger, be- ing sometimes -4 feet in .diameter, and 6 or 8 feet long. Generally two, or even three, are placed in each furnace, as shown in fig. 1, so that the fire of the single furnace, a, plays all round them. The doors for charging the retorts are at one end, b, (fig. 2), and the pipe for carrying off the vola- tile products at the other, e, by which they are con- ducted, first to the tar- condenser, rf, and finally through a worm in a large tub, e, where the crude acetic acid is collected.

Of course, in different localities an endless va- riety of modifications of the process are employed. In the Forest of Dean, instead of cylindrical re- torts, square sheet-iron boxes are used, 4 ft. 6 in. by 2 ft. 9 in., which are heated in large square ovens.

With regard to the relative advantages of cylindrical retorts or square boxes,, it should be remarked that the cylinders are more adapted for the distilla- tion of the large billets of Gloucestershire, and the refuse ship timber of Glasgow, Newcastle, and Liverpool ; but, on the other hand, where light wood is used, such as that generally carbonized in the Welsh factories, the square ovens answer better.

The most recent and ingenious improvement in the manufacture of pyroligneous acid is that patented by the late Mr. A. G. Halliday, of Manchester, and adopted by several large manufacturers. The process consists in effecting the destructive distillation of waste mate- rials, such as saw-dust and spent dye-woods, by causing them to pass in continuous motion through heated retorts. For this purpose the materials, which are almost in a state of powder, are introduced into a hopper, h (fig. 3), whence they descend into the retort, b,

ACETIC ACID.

11

being kept all the while in constant agitation, and at the same time moved forward to the other end of the retort by means of an endless screw, s. By the time they arrive there, the charge has been completely carbonized, and all the pyroligneous acid evolved at the exit tube, t. The residuary charcoal falls through the pipe d into a vessel of water, e, whilst the volatile products escape at f, and are condensed in the usual way.

Several of these retorts are generally set in a furnace side by side, the retorts are only 14 inches in diameter, and eight of these retorts produce in 24 hours as much acid as 16 retorts 3 feet in diameter upon the old system. In the manufacturing districts of Lancashire and Yorkshire, where such immense quantities of spent dye-woods accumulate, and have proved a source of annoyance and expense for their removal, this process has afforded a most important means of economically converting them into valuable products — charcoal and acetic acid.

Mention should also be made of Messrs. Solomons and Azulay's patent for employing superheated steam to effect the carbonization of the wood, which is passed directly into the mass of materials. Since the steam accompanies the volatile products, it necessarily dilutes the acid ; but this is in a great degree compensated for by employing these vapors to con- centrate the distilled products, by causing them to traverse a coil of tubing placed in a pan of the distillates.

As regards the yield of acetic acid from the different kinds of wood, some valuable facts have been collected and tabulated by Stolze, in his work on Pyroligneous Acid : —

One Pound of Wood.	Weight of Acid.	Carbonate of Potassa neu- tralized by One Ounce of Acid.	Weight of Charcoal.
White birch • - Betula alba ... Red birch - - Fagus sylvatica Large-leaved linden Tilia pataphylla Oak ... Quercus robur - Ash ... Fraxinus excelsior Horse chestnut - Esculus hippocastanus Lombardy poplar - Populus dilatata White poplar - Populus alba - Bird cherry - - Prunus padus - Basket willow - Salix - Buckthorn - - Rhamnus - - - - Logwood - - Hematoxylon campechianum Alder - - - Alnus .... Juniper - - - Juniperus communis - White fir - - Pjnus abies Common pine - Pinus sylvestris Common savine - Juniperus sabina Red fir - - - Abies pectinata	ozs. n 61 61 H n n 7 n n li il • il n 6| i 6f	grs. 55 54 52 50 44 41 40 39 37 35 34 35 30 29 29 28 27 25	ozs. 31 8* H 3f H ■ 3& n H n 2 H 31 at 3$ 3J

12 ACETIC ACID.

Properties of the crude Pyroligneous Acid. — The crude pyroligneous acid possesses the properties of acetic acid, combined -with those of the pyrogenous bodies with which it is associated. As first obtained, it is black from the large quantity of tar which it holds in solution ; and although certain resins are removed by redistillation, yet it is impossible to remove some of the empyreumatic oils by this process, and a special purification is necessary.

In consequence of the presence of creosote, and other antiseptic hydrocarbons, in the crude pyroligneous acid, it possesses, in a very eminent degree, anti-putrescent properties. Flesh steeped in it for a few hours may be afterwards dried in the air without corrupting ; but it becomes hard, and somewhat leather-like : so that this mode of preservation does not answer well for butcher's meat. Fish are sometimes cured with it.

Purification of Pyroligneous Acid. — This is effected either, 1st, by converting it into an acetate, — acetate of lime or soda, — and then, after the purification of these salts by exposure to heat sufficient to destroy the tar, and repeated recrystallization, liberating the acid again by distilling with a stronger acid, e. g. sulphuric.

Or, 2d, by destroying the pyrogenous impurities by oxidizing agents, such as binoxide of manganese in the presence of sulphuric acid, &c.

The former is the method generally adopted.

After the naphtha has been expelled, the acid liquor is run off into tanks to deposit part of its impurities ; it is then syphoned off into another vessel, in which is either milk of lime, quicklime, or chalk ; the mixture is boiled for a short time, and then allowed to stand for 24 hours to deposit the excess of lime with any impurities which the latter will carry down with it. The supernatant liquor is then pumped into the evaporating pans.

The evaporation is effected either by the heat of a fire applied beneath the evaporating pans, or more frequently by a coil of pipe in the liquor, through which steam is passed — the liquor being kept constantly stirred, and the impurities which rise to the surface during the process carefully skimmed off.

From time to time, as the evaporation advances, the acetate of lime which separates is removed by ladles, and placed in baskets to drain ; and the residual mother liquor is evaporated to dryness. This mass, by ignition, is converted into carbonate of lime and acetone.

If the acetate of lime has been procured by directly saturating the crude acid, it is called brown acetate ; if from the acid once purified by redistillation, it is called gray acetate.

From this gray acetate of lime, acetate of soda is now prepared, by adding sulphate of soda to the filtered solution of the acetate of lime. In performing this operation, it is highly important to remember that, for every equivalent of acetate of lime, it is necessary to add two equivalents of sulphate of soda, on account of the formation of a double sulphate of soda and lime. The equation representing the change being : —

CaO, C4 H3 O3 + 2(NaO, SO3) = NaO,04 H3 O3 -f- CaO, SO3. NaO, SO3

Acetate of lime. Acetate of soda. Double sail.

Or, if sulphuric acid be considered as a bibasie acid, which this very reaction so strongly justifies —

C4 H3 (Ca) 04 + Naa S= O8 = C4 H3 (Na) O4 + jM S= 08

Acetate of lime. Sulphate of soda. Acetate of soda. Double salt.

If this point be neglected, and only one equivalent of sulphate of soda be used, one-half of the acetate of lime may escape decomposition, and thus be lost.

After the separation of the double salt, the solution of acetate of soda is drawn off, any impurities allowed to subside, and then concentrated by evaporation until it has a density of 4-3 — when the acetate of soda crystallizes out, and may be further purified, if requisite, by another re-solution and re-crystallization. The contents of the mother liquors are con- verted into acetone and carbonate of soda, as before.

The crystallized acetate of soda is now fused in an iron pot, at a temperature of about 400°, to drive off the water of crystallization, the mass being kept constantly stirred. A stronger heat must not be applied, or we should effect the decomposition of the salt.

For the production of the acetic acid from this salt, a quantity of it is put into a stout copper still, and a deep cavity made in the centre of the mass, into which sulphuric acid of specific gravity 1-84 is poured in the proportion of 35 per cent, of the weight of the salt; the walls of the cavity are thrown in upon the acid, the whole briskly agitated with a wooden spatula. The head of the still is then luted, and connected with the condensing worm, and the distillation carried on at a very gentle heat. The worm should be of silver or porcelain, as also the still head ; and even silver solder should be used to connect the joinings in the body of the still. The still is now generally heated by a steam "jacket." See Distillation.

The acid which passes over is nearly colorless, and has a specific gravity of l-05. That

ACETIC ACID.

13*

which collects at the latter part of the operation is liable to be somewhat empyreumatic, and therefore, before this point is reached, the receiver should be changed ; and throughout the entire operation, care should be taken to avoid applying too high a temperature, as the flavor and purity of the acid will invariably suffer.

Any trace of empyreuma may be removed from the acid by digestion with animal char- coal and redistillation.

A considerable portion of this acid crystallizes at a temperature of from 40° to 50° F, constituting what is called glacial acetic acid, which is the oompound C H4 Ol (or C4 H3 O3, HO).

For culinary purposes, pickling, &c, the acid of specific gravity 1-05 is diluted with five times its weight in water, which renders it of the same strength as Revenue proof vinegar.

Several modifications and improvements of this process have recently been introduced, which require to be noticed.

The following process depends upon the difficult solubility of sulphate of soda in strong acetic acids : — 100 lbs. of the pulverized salt being put into a hard glazed stoneware re- ceiver, or deep pan,' from 35 to 36 lbs. of concentrated sulphuric acid are poured in one stream upon the powder, so as to flow under it. The mixture of the salt and acid is to be made very slowly, in order to moderate the action and the heat generated, as much as possible. After the materials have been in intimate contact for a few hours, the decompo- sition is effected ; sulphate of soda in crystalline grains will occupy the bottom of the vessel and acetic acid the upper portion, partly liquid and partly in crystals. A small portion of pure acetate of lime added to the acid will free it from any remainder of sulphate of soda, leaving only a little acetate in its place ; and though a small portion of sulphate of soda may still remain, it is unimportant, whereas the presence of any free sulphuric acid would be very injurious. This is easily detected by evaporating a little of the liquid, at a moderate heat, to dryness, when that mineral acid can be distinguished from the neutral soda sulphate. This plan of superseding a troublesome distillation, which is due to M. Mollerat, is one of the greatest improvements in this process, and depends upon the insolubility of the sulphate of soda in acetic acid. The sulphate of soda thus recovered, and well drained, serves anew to decompose acetate of lime ; so that nothing but this cheap earth is consumed in carrying on the manufacture. To obtain absolutely pure acetic acid, the above acid has to be distilled in a glass retort.

Vfalckel recommends the use of hydrochloric instead of sulphuric acid for decomposing the acetate.

The following is his description of the details of the process : —

" The crude acetate of lime is separated from the tarry bodies which are deposited on neutralization, and evaporated to about one-half its bulk in an iron pan. Hydrochloric acid is then added until a distinctly acid reaction is produced on cooling ; by this means the resinous bodies are separated, and come to the surface of the boiling liquid in a melted state, whence they can be removed by skimming, while the compounds of lime, with creo- sote, and other volatile bodies, are likewise decomposed, and expelled on further evapora- tion. From 4 to 6 lbs. of hydrochloric acid for every 33 gallons of wood vinegar is the average quantity required for this purpose. The acetate, having been dried at a high tem- perature on iron plates, to char and drive off the remainder of the tar and resinous bodies, is then decomposed, by hydrochloric acid, in a still with a copper head and leaden condens- ing tube. To every 100 lbs. of salt about 90 to 95 lbs. of hydrochloric acid of specific gravity 1-16 are required. The acid comes over at a temperature of from 100° to 120° C. (212° to 248° F.), and is very slightly impregnated with empyreumatic products, while a mere cloud is produced in it by nitrate of silver. The specific gravity of the product varies from l-058 to 1-061, and contains more than 40 per cent, of real acid ; but as it is seldom required of this strength, it is well to dilute the 90 parts of hydrochloric acid with 25 parts of water. These proportions then yield from 95 to 100 parts of acetic acid of specific gravity 1'015.

This process is recommended on the score of economy and greater purity of product. The volatile empyreumatic bodies are said to be more easily separated by the use of hydro- chloric than sulphuric acid ; moreover, the chloride of calcium being a more easily fusible salt than the sulphate of lime, or even than the double sulphate of lime and soda, the acetic acid is more freely evolved from the mixture. The resinous bodies also decompose sulphuric acid towards the end of the operation, giving rise to sulphurous acid, sulphuretted hydrogen, &c, which contaminate the product.

Impurities and Adulterations. — In order to prevent the putrefactive change which often takes place in vinegar when carelessly prepared by the fermentation of malt wine, &c, it was at one time supposed to be necessary to add a small quantity of sulphuric acid. This notion has long since been shown to be false ; nevertheless, since the addition of 1 part of sulphuric acid to 1,000 of vinegar was permitted by an excise regulation, and thus the practice has received legal sanction, it is still continued by many manufacturers. So long as the quantity is retained within these limits, and if pure sulphuric acid be used (great care

14

ACETLMETRY.

being taken that there is no arsenic present in such oil of vitriol, as is not unfrequently the case in inferior varieties), no danger can ensue from the habit ; but occasionally the quantity is much overpassed by dishonest dealers, of whom it is to be hoped there are but few.

Dr. Ure mentions having found, by analysis, in a sample of vinegar, made by one of the most eminent London manufacturers, with which he supplied the public, no less than l^o grains of the strongest oil of vitriol per gallon, added to vinegar containing only 3-^. per cent, of real acetic acid, giving it an apparent strength after all of only 4 per cent., whereas standard commercial vinegar is rated at 5 per cent.

The methods of determining sulphuric acid will be given, once for all, under the head of Acidimetry, and therefore need not be described in every case where it occurs ; the same remark applies to hydrochloric acid and others.

Hydrochloric acid is rarely intentionally added to vinegar ; but it may accidentally be present when the pyroligneous acid has been purified by Volckel's process. It is detected by the precipitate which it gives with solution of nitrate of silver in the presence of nitric acid.

Nitric acid is rarely found in vinegar. For its method of detection, see Nitric Actd.

Wine vinegar generally contains tartaric acid and tartrates ; but it is purified from them by distillation.

Sulphurous acid is occasionally met with in pyroligneous acid. This is recognized by its bleaching action on delicate vegetable colors, and by its conversion, under the influence of nitric acid, into sulphuric acid, which is detected by chloride of barium.

Sulphuretted hydrogen is detected by acetate of lead giving a black coloration or pre- cipitate. .

Metallic Salts. — If care be not taken in constructing the worm of the still of silver or earthenware, distilled acetic acid is frequently contaminated with small quantities of metal from the still, copper, lead, tin, &c. These metals are detected by the addition of sulphu- retted hydrogen, as is fully discussed under the head of the individual metals. Copper is the most commonly found, and it may be detected in very minute quantities by the blue color which the solution assumes on being supersaturated with ammonia.

It is not uncommon to add to pyroligneous acid, a little coloring matter and acetic ether, to give it the color and flavor of wine or malt vinegar ; but this can hardly be called an adulteration.

The presence of the products of acetification of eider may be detected by neutralizing the vinegar with ammonia, and then adding solution of acetate of lime. Tartrate of lime is, of course, precipitated from the wine vinegar, while the pearly malic acid of the cider affords no precipitate with the lime, but may be detected by acetate of lead, by the glistening pearly scales of malate of lea'd, hardly soluble in the cold.

Acetic acid is extensively employed in the arts, in the manufacture of the various ace- tates, especially those of alumina and iron, so extensively employed in calico printing as mordants, sugar of lead, &c. It is likewise used in the preparation of varnishes, for dis- solving gums and albuminous bodies ; in the culinary arts, especially in the manufacture of pickles and other condiments ; in medicine, externally, as a local irritant, and internally, to allay fever, &c.

For the treatment in cases of poisoning, we refer to Taylor, Pereira, and other medical authorities. — H. M. W.

ACETIMETRY. Determination of the Strength of Vinegar. — If in vinegars we were dealing with mixtures of pure acetic acid and water, the determination of the density might, to a certain extent, afford a criterion of the strength of the solution ; but vinegar, especially that obtained from wine and malt, invariably contains gluten, saccharine, and mucilaginous matters, which increase its density and render this method altogether fallacious.

The only accurate means of determining the strength of vinegar is by ascertaining the quantity of carbonate of soda or potash neutralized by a given weight of the vinegar under examination. This is performed by adding to the vinegar a standard solution of the alka- line carbonate of known strength from a bructte, until, after boiling to expel the carbonic acid, a solution of litmus previously introduced into the liquid is distinctly reddened.

The details of this process, which is equally applicable to mineral and other organic acids, will be found fully described under the head of Acidimetry.

Roughly, it may be stated that every 53 grains of the pure anhydrous carbonate of soda, or every 69 grains of carbonate of potassa (i. e. one equivalent), correspond to 60 grains of acetic acid (C H4 O4).*

It is obvious that preliminary examinations should be made to ascertain if sulphuric, hydrochloric, or other mineral acids are present ; and, if so, their amount determined, otherwise they will be reckoned as acetic acid.

The British malt vinegar is stated in the London Pharmacopoeia to require a drachm

* In most cases where, in commercial language, mention is made of real acetic acid, the hypotheti- cal compound C4H303 is meant; but it would be better in future always to give the percentage of acetic acid C4IT404 — for the bodyC4H303 is altogether hypothetical — never having yet been discovered. See the remarks on Anhydrous Acetic Acid at the commencement of this article. — H. M. "W.

ACETYL.

15

(60 grains) of crystallized carbonate of soda (which contains 10 equivalents of water of crystallization) for saturating a fluid ounce, or 4-46 grains ; it contains, in fact, from 4-6 to 5 per cent, of real acetic acid.

The same authorities consider that the purified pyroligneous acid should require 87 grains of carbonate of soda for saturating 100 grains of the acid.

Dr. Ure suggests the use of the bicarbonate of potash. Its atomic weight, referred to hydrogen as unity, is 100*584, while the atomic weight of acetic acid is 51-563; if we estimate 2 grains of the bicarbonate as equivalent to 1 of the real acidj we shall commit no appreciable error. Hence a solution of the carbonate containing 200 grains in 100 measures will form an acetimeter of the most perfect and convenient kind ; for the meas- ures of test liquid expended in saturating any measure — for instance, an ounce or 1,000 grains of acid — will indicate the number of grains of real acetic acid in that quantity. Thus, 1,000 grains of the above proof would require 50 measures of the acetimetrical alka- line solution, showing that it contains 50 grains of real acetic acid in 1,000, or 5 per cent

Although the bicarbonate of potash of the shops is not absolutely constant in compo- sition, yet the method is no doubt accurate enough for all practical purposes.

The acetimetrical method employed by the Excise is that recommended by Messrs. J. and P. Taylor,* and consists in estimating the strength of the acid by the specific gravity which it acquires when saturated by hydrate of lime. Acid which contains 5 per cent, of real acid is equal in strength to the best malt vinegar, called by the makers No. 24, and is assumed as the standard of vinegar strength, under the denomination of " proof vinegar."f Acid which contains 40 per cent, of real acetic acid is, therefore, in the language of the Revenue, 35 per cent, over proof; it is the strongest acid on which duty is charged by the acetimeter. In the case of vinegars which have not been distilled, an allowance is made for the increase of weight due to the mucilage present ; hence, in the acetimeter sold by Bate, a weight, marked m, is provided, and- is used in trying such vinegars. As the hydrate of lime employed causes the precipitation of part of the mucilaginous matter in the vine- gar, it serves to remove this difficulty to a certain extent. (Pereira.) — H. M. W.

AGETONE, syn. pyroacetic spirit, mesitic alcohol, pyroacetic ether. C6 H6 O2. A volatile fluid usually obtained by the distillation of the acetates of the alkaline earths. It is also obtained in a variety of operations where organic matters are exposed to high tem- perature. Tartaric and citric acids yield it when distilled. Sugar,, gum, or starch, when mixed with lime and distilled, afford acetone. If crude acetate of lime be distilled, the acetone is accompanied by a small quantity of ammonia and traces of methylamine. The latter is due to the nitrogen contained in the wood -, the distillate from which was used in the preparation of the acetate of lime. Crude acetone may be purified by redistilling it in a water-bath. A small quantity of slaked lime should be added previous to distillation, to combine with any acid that may be present. When pure, it forms a colorless mobile fluid, boiling at 133° F. Its density at 18° is 0-7921, at 32° it is 0-8140. The density of its vapor was found by experiment to be 2-00; theory requires 2.01, supposing six volumes of carbon vapor, twelve volumes of hydrogen, and two volumes of oxygen to be condensed to four volumes. When acetone is procured from acetate of lime, two equivalents of the latter are decomposed, yielding one equivalent of acetone, and two equivalents of car- bonate of lime. It has been found that a great number of organic acids, when distilled under similar circumstances, yield bodies bearing the same relation to the parent acid that acetone does to acetic acid : this fact has caused the word acetone to be used of late in a more extended sense than formerly. The word ketone is now generally used to express a neutral substance derived by destructive distillation from an acid, the latter losing the elements of an equivalent of carbonic acid during the decomposition. Theoretical chemists are somewhat divided with regard to the rational formula? of the ketones. An overwhelm- ing weight of evidence has been brought by Gerhardt and his followers, to prove that they should be regarded as aldehydes in which an equivalent of hydrogen is replaced by the radical of an alcohol. Thus common acetone (C6 HG O2) is aldehyde (C4 H4 O2), in which one equivalent of hydrogen is replaced by methyle, C2 H3.

Acetone dissolves several gums and resins, amongst others sandarach. Wood spirit, which sometimes, owing to the presence of impurities, refuses to dissolve sandarach, may be made to do so by the addition of a small quantity of acetone.

When treated with sulphuric acid and distilled, acetone yields a hydrocarbon called mesitylene or mesitylole, C18 H12.— C. G. W.

ACETYL. Two radicals are known by this name, namely, C4 H3 and C4 II3 02. Their nomenclature has not, as yet, been definitely settled. Dr. Williamson proposes to call it othyl. The hydrocarbon C4 H3 is now assumed to exist in aldehyde, which can be regarded as formed on the type two atoms of water, thus : —

In the above formula we have two atoms of water, in which 1 equivalent of hydrogen is

* Quarterly Journal of Science, vi, 255.

t BS Geo. III., e. 65.

16

ACID.

replaced by the non-oxidized radical C4 H3, which may very conveniently be named aldyle, to recall its existence in aldehyde. — C. G. W.

ACID. (Acidus, sour, L.) The term acid was formerly applied to bodies which were Bour to the taste, and in popular language the word is still so used. It is to be regretted that the necessities of science have led to the extension of this word to any bodies com- bining with bases to form salts, whether such combining body is sour or otherwise. Had not the term acid been established in language as expressing a sour body, there would have been no objection to its use ; but chemists now apply the term to substances which are not sour, and which do not change blue vegetable colors ; and consequently they fail to convey a correct idea to the popular mind.

Hobbes, in his " Computation or Logic," says, " A name is a word taken at pleasure to serve for a mark which may raise in our mind a thought like to some thought we had before, and which, being pronounced to others, may be to them a sign of what thought the speaker had, or had not, before in his mind." This philosopher thus truly expresses the purpose of a name ; and this purpose is not fulfilled by the term acid, as now employed.

Mr. John Stuart Mill, in his " System of Logic," thus, as it appears not very happily, endeavors to show that the term acid, as a scientific term, is not inappropriate or incorrect.

" Scientific definitions, whether they are definitions of scientific terms, or of common terms used in a scientific sense, are almost always of the kind last spoken of : their main purpose is to serve as the landmarks of scientific classification. And, since the classifica- tions in any science are continually modified as scientific knowledge advances, the defini- tions in the sciences are also constantly varying. A striking instance is afforded by the words acid and alkali, especially the former. As experimental discovery advanced, the substances classed with acids have been constantly multiplying ; and, by a natural conse- quence, the attributes connoted by the word have receded and become fewer. At first it connoted the attributes of combining with an alkali to form a neutral substance (called a salt), being compounded of a base and oxygen, causticity to the taste and touch, fluidity, &c. The true analysis of muriatic acid into chlorine and hydrogen caused the second property, composition from a base and oxygen, to be excluded from the connotation. The same discovery fixed the attention of chemists upon hydrogen as an important element in acids ; and more recent discoveries having led to the recognition of its presence in sul- phuric, nitric, and many other acids, where its existence was not previously suspected, there is now a tendency to include the presence of this element in the connotation of the word. But carbonic acid, silica, sulphurous acid, have no hydrogen in their composition ; that property cannot, therefore, be connoted by the term, unless those substances are no longer to be considered acids. Causticity and fluidity have long since been excluded from the characteristics of the class by the inclusion of silica and many other substances in it ; and the formation of neutral bodies by combination with alkalis, together with such electro- chemical peculiarities as this is supposed to imply, are now the only differentia which form the fixed connotation of the word acid as a term of chemical science."

The term Alkali, though it is included by Mr. J. S. Mill in connection with acid in his remarks, does not stand, even as a scientific term, in the objectional position in which we find acid. Alkali is not, strictly speaking, a common name to which any definite idea is attached. Acid, on the contrary, is a word commonl;/ employed to signify sour. With the immense increase which organic chemistry has given to the number of acids, it does appear necessary, to avoid confusion, that some new arrangement, based on a strictly logical plan, should be adopted. This is, however, a task for a master mind ; and possibly we must wait for another generation before such a mind appears among us.

In this Dictionary all the acids named will be found under their respective heads ; as Acetic, Nitric, Sulphuric Acids, &e.

ACIDIFIER. Any simple or compound body whose presence is necessary fof the pro- duction of an acid ; as oxygen, chlorine, bromine, iodine, fluorine, sulphur, &c, &c.

ACIDIMETER. An instrument for measuring the strength or quantity of real acid contained in a free state in liquids. The construction of that instrument is founded on the principle that the quantity of real acid present in any sample is proportional to the quan- tity of alkali which a given weight of it can neutralize. The instrument, like the alkalim- eter (see Alkalimeter), is made to contain 1,000 grains in weight of pure distilled water, and is divided accurately into 100 divisions, each of which therefore represents 10 grains of pure distilled water ; but as the specific gravity of the liquids which it serves to measure may be heavier or lighter than pure water, 100 divisions of such liquids are often called 1,000 grains' measure, irrespectively of their weight (specific gravity), and accordingly 10-20, &c. divisions of the acidimeter are spoken of as 100-200, &c. grains' measure ; that is to say, as a quantity or measure which, if filled with pure water, would have weighed that number of grains.

ACIDIMETRY. Acidimetry is the name of a chemical process of analysis by means of which the strength of acids — that is to say, the quantity of pure free acid contained in a liquid — can be ascertained or estimated. The principle of the method is based upon Dal-

AOIDIMETRY.

17

Saturate or neutralize 1 eqv. = 49 parts in weight of pure oil of vitriol (sp. gr. 1-8485), or 1 equiv. of any other acid.

ton's law of chemical combinations ; or, in other words, upon the fact that, in order to pro- duce a complete reaction, a certain definite weight of reagent is required.

If, for example, we take 1 equivalent, or 49 parts in weight, of pure oil of vitriol of specific gravity 1-S485, dilute it (of course within limits) with no matter what quantity of water, and add thereto either soda, potash, magnesia, ammonia, or their carbonates, or in fact any other base, until the acid is neutralized — that is to say, until blue litmus-paper is no longer, or only very faintly, reddened when moistened with a drop of the acid liquid under examination, — it will be found that the respective weights of each base required to produce that effect will greatly differ, and that with respect to the bases just mentioned these weights will be as follows : —

Soda (caustic) 1 equiv. =31 parts in weight"

Potash (caustic) " = 47 "

Ammonia " = 17 "

Carbonate of soda " = 53 "

Carbonate of potash " = 69 "

This beiDg the case, it is evident that if we wish to ascertain by such a method the quantity of sulphuric acid or of any other acid contained in a liquid, it will be necessary, on the one hand, to weigh or measure accurately a given quantity of that liquid to be examined, and, on the other hand, to dissolve in a known volume of water the weight above mentioned of any one of the bases just alluded to, and to pour that solution gradually into that of the acid until neutralization is obtained ; the number of volumes of the basic solution which will have been required for the purpose will evidently indicate the amount in weight of acid which existed in the liquid under examination. Acidimetry is therefore exactly the reverse of alkalimetry, since in principle it depends on the number of volumes of a solu- tion of a base diluted with water to a definite strength, which are required to neutralize a known weight or measure of the different samples of acids.

The solution containing the known weight of base, and capable therefore of saturating a known weight of acid, is called a " test-liquor;" and an aqueous solution of ammonia, of a standard strength, as first proposed by Dr. Ure, affords a most exact and convenient means of effecting the purpose, when gradually poured from a graduated dropping-tube or acidimeter into the sample of acid to be examined.

The strength of the water of ammonia used for the experiment should be so adjusted that 1,000 grains' measure of it (that is, 100 divisions of the alkalimeter) really contain one equivalent (17 grains) of ammonia, and consequently neutralize one equivalent of any one real acid. The specific gravity of the pure water of ammonia employed as a test for that purpose should be exactly 0-992, and when so adjusted, 1,000 grains' measure (100 divisions of the acidimeter) will then neutralize exactly

40 grains, or one equivalent, of sulphuric acid (dry).

oil of vitriol, sp. gr. 1.8485. hydrochloric acid (gas, dry), nitric acid (dry), crystallized acetic acid, oxalic acid, tartaric acid, acetic acid.

49 37.5

54

60

45 150

51 And so forth with the other acids.

A standard liquor of ammonia of that strength becomes, therefore, a universal acid- imeter, since the number of measures or divisions used to effect the neutralization of 10 or of 100 grains of any one acid, being multiplied by the atomic weight or equivalent number of the acid under examination, the product, divided by 10 or by 100, will indicate the per- centage of real acid contained in the sample ; the proportion of free acid being thus determined with precision, even to Jj of a grain, in the course of five minutes, as will be shown presently.

The most convenient method of preparing the standard liquor of ammonia of that specific gravity is by means of a glass bead, not but that specific gravity bottles and hydrometers may, of course, be employed ; but Dr. Ure remarks, with reason, that they furnish incomparably more tedious and less delicate means of adjustment. The glass bead, of the gravity which the test-liquor of ammonia should have, floats, of course, in the middle of such a liquor, at the temperature of 60° F. ; but if the strength of the liquor becomes attenuated by evaporation, or its temperature increased, the attention of the operator is immediately called to the fact, since the difference of a single degree of heat, or the loss of a single hundredth part of a grain of ammonia per cent., will cause the bead to sink to the bottom — a degree of precision which no hydrometer can rival, and which could not otherwise be obtained, except by the troublesome operation of accurate weighing. Whether the solution remains uniform in strength is best ascertained by introducing into the bottle containing the ammonia test-liquor two glass beads, so adjusted that one, being

Vol. III.— 2

18 ACIDLHETRY.

very slightly heavier than the liquid, may remain at the bottom ; whilst the other, being very slightly lighter, reaches the top, and remains just under the surface as long as the liquor is in the normal state ; but when, by the evaporation of some ammonia, the liquor becomes weaker, and consequently its specific gravity greater, the bead at the bottom rises towards the surface, in which case a few drops of strong ammonia should be added to restore the balance.

An aqueous solution of ammonia, of the above strength and gravity, being prepared the acidimetrical process is in every way similar to that practised in alkalimetry ; that is to say, a known weight, for example, 10 or 100 grains of the sample of acid to be examined are poured into a sufficiently large glass vessel, and diluted, if need be, with water, and a little tincture of litmus is poured into it, in order to impart a distinct red color to it ; 100 divisions, or 1,000 grains' measure, of the standard ammonia test-liquor above alluded to, are then poured into an alkalimeter (which, in the present case, is used as an acidimeter), and the operator proceeds to pour the ammonia test-liquor from the alkalimeter into the vessel containing the acid under examination, in the same manner, and with the same precautions used in alkalimetry (see Alkalimetry), until the change of color, from red to blue, of the acid liquor in the vessel indicates that the neutralization is complete, and the operation finished.

Let us suppose that 100 grains in weight of a sample of sulphuric acid, for example, have required 61 divisions (G10 water-grains' measure) of the acidimeter for their complete neutralization, since 100 divisions (that is to say, a whole acidimeter full) of the test-liquor of ammonia are capable of neutralizing exactly 49 grains — one equivalent — of oil of vitriol, of specific gravity, 1-8485, it is clear that the 61 divisions employed will have neutralized 29-89 of that acid, and, consequently, the sample of sulphuric acid examined contained that quantity per cent, of pure oil of vitriol, representing 24 '4 per cent, of pure anhydrous sulphuric acid : thus —

Divisions. Oil of Vitriol.

100 : 49 :: 01 : x = 29-89.

Anhydrous Acid. 100 : 40 :: 61 : z = 24-4.

The specific gravity of an acid of that strength is 1-2178.

In the same manner, suppose that 100 grains in weight of hydrochloric acid have required 90 divisions (900 grains' measure) of the acidimeter for their complete neutraliza- tion, the equivalent of dry hydrochloric acid gas being 36-5, it is clear that since 90 divisions only of the ammonia test-liquor have been employed, the sample operated upon must have contained per cent, a quantity of acid equal to 33-30 of dry hydrochloric acid gas in solution, as shown by the proportion : —

Divis. Hydrochloric acid. 100 : 36-5 :: 90 : x = 32-85.

The specific gravity of such a sample would be 1-1646.

Instead of the ammonia test-liquor just alluded to, it is clear that a solution containing one equivalent of any other base — such as, for example, carbonate of soda, or carbonate of potash, caustic lime, &c. — may be used for the purpose of neutralizing the acid under examination. The quantity of these salts required for saturation will of course indicate the quantity of real acid, and, by calculation, the percentage thereof in the sample, thus : — The equivalent of pure carbonate of soda 53, and that of carbonate of potash 69, either of these weights will represent one equivalent, and consequently 49 grains of pure oil of vitriol, 36-5 of dry hydrochloric acid, 60 of crystallized, or 51 of anhydrous acetic acid, and so on. The acidimetrical assay is performed as follows : —

If with carbonate of soda, take 530 grains of pure and dry carbonate of soda, obtained by igniting the bicarbonate of that base (sec Alkalimetry), and dissolve them in 10,000 water grains' measure (1,000 acidimetrical divisions) of distilled water. It is evident that each acidimeter full (100 divisions) of such a solution will then correspond to one equivalent of any acid ; and accordingly, if the test-liquor of carbonate of soda be poured from the acidimeter into a weighed quantity of any acid, with the same precautions as before, until the neutralization is complete, the number of divisions employed in the operation will, by simple rule of proportion, indicate" the quantity of acid present in the sample as before. Pure carbonate of soda is easily obtained by recrystallizing once or twice the crystals of'' carbonate of soda of commerce, and carefully washing them. By heating them gradually they melt, and at a very low red heat entirely lose their water of crystallization and become converted into pulverulent anhydrous neutral carbonate of soda, which should be kept in well closed bottles.

When carbonate of potash is used, then, since the equivalent of carbonate of potash is 69, the operator should dissolve 690 grains of it in the 10,000 grains of pure distilled water, and the acidimeter being now filled with this test-liquor, the assay is carried on again precisely in the same manner as before. Neutral carbonate of potash for acidimetrical use

ACIDIMETRY.

19

is prepared by heating the bicarbonate of that base to redness, in order to expel one equivalent of its carbonic acid ; the residue left is pure neutral carbonate of potash ; and in order to prevent its absorbing moisture, it should be put, whilst still hot, on a slab placed over concentrated sulphuric acid, or chloride of calcium, under a glass bell, and, when sufficiently cool to be handled, transferred to bottles carefully closed.

To adapt the above methods to the French weights and measures, now used also gener- ally by the German chemist, we need only substitute 100 decigrammes for 100 grains, and proceed with the graduation as already described.

A solution of caustic lime in cane sugar has likewise been proposed by M. Peligot for acidi metrical purposes. To prepare such a solution, take pure caustic lime, obtained by heating Carara marble among charcoal in a furnace ; when sufficiently roasted to convert it into quicklime, slake it with water, and pour upon the slaked lime as much water as is necessary to produce a milky liquor ; put this milky liquor iu a bottle, and add thereto, in the cold, a certain quantity of pulverized sugar-candy ; close the bottle with a good cork, and shake the whole mass well. After a certain time it will be observed that the milky liquid has become very much clearer, and perhaps quite limpid ; filter it, and the filtrate will be found to contain about 50 parts of lime for every 100 of sugar employed. The liquor should not be heated, because saccharate of lime is much more soluble in cold than in hot water, and if heat were applied it would become turbid or thick, though on cooling it would become clear again.*

A concentrated solution of lime in sugar being thus obtained, it should now be diluted to such a degree that 1,000 water grains' measure of it may be capable of saturating exactly one equivalent of any acid, which is done as follows : — Take 100 grains of hydrochloric acid of specific gravity 1'1812, that weight of acid contains exactly one equivalent = 36-5 of pure hydrochloric acid gas ; on the other hand, fill the acidimeter up to 0 (zero) with the solution of caustic lime in sugar prepared as abovesaid, and pour the contents into the acid until exact, neutralization is obtained, which is known by testing with litmus paper in the usual manner already described. If the whole of the 100 divisions of the acidimeter had been required exactly to neutralize the 100 grains1 weight of hydrochloric acid of the specific gravity mentioned, it would have been a proof that it was of the right strength ; but suppose, on the contrary, that only 50 divisions of the lime solution in the acidimeter have been sufficient for the purpose, it is evident that it is half too strong, or, in other words, one equivalent of lime (=28) is contained in those 50 divisions instead of in*100. Pour, there- fore, at once, 50 divisions or measures of that lime-liquor into a glass cylinder accurately divided into 100 divisions, and fill up the remaining 50 divisions with water ; stir the whole well, and 100 divisions of the lime-liquor will, of course, now contain as much lime as was contained before in the 50 ; or, in other words, 100 acidimetrical divisions will now contain 1 equivalent of lime, and therefore will be capable of exactly neutralizing 1 equivalent of any acid.

When, however, saccharate of lime is used for the determination of sulphuric acid, it is necessary to dilute it considerably, for otherwise a precipitate of sulphate of lime would be produced. This reagent, moreover, is evidently applicable only to the determination of such acids the lime salts of which are soluble in water.

Instead of a solution of caustic lime in sugar, a clean dry piece of white Carara marble may be used. Suppose, for example, that the acid to be assayed is acetic acid, the instruc- tions given by Brande are as follows : — A clean dry piece of marble is selected and accu- rately weighed ; it is then suspended by a silk thread into a known quantity of the vinegar or acetic acid to be examined, and which is cautiously stirred with a glass rod, so as to mix its parts, but without detaching any splinters from the weighed marble, till the whole of the acid is saturated, and no further action on the marble is observed. The marble is then taken out, washed with distilled water, and weighed ; the loss in weight which it has sustained may be considered as equal to the quantity of acetic acid present, since the atomic weight of carbonate of lime (=50) is very nearly the same as that of acetic acid (=51'). Such a process, however, is obviously less exact than those already described.

But whichever base is employed to prepare the test-liquor, it is clear that the acid tested with it must be so far pure as not to contain any other free acid than that for which it is tested, for in that case the results arrived at would be perfectly fallacious. Unless, therefore, the operator has reason to know that the acid, the strength of which has to be examined by that process, is genuine of its kind, he must make a qualitative analysis to satisfy himself that it is so ; for in the contrary case the acid would not be in a fit state to be submitted to an acidimetrical assay.

We shall terminate this article by a description of Liebig's acidimetrical method of determining the amount of prussic acid contained in solutions ; for example, in medicinal prussic acid, in laurel and bitter almond water, essence of bitter almonds, and cyanide of potassium. The process is based upon the following reaction : — When an excess of caustic

_ * The directions given by M. Violette for the preparation of Sacclmrate of Lime are as follows: — Digest in the cold 50 grammes of slaked caustic lime in 1 litre of water containing 100 grammes of sugar.

20 ACIPENSEE.

potash is poured in a solution which contains prussic acid, cyanide of potassium is, of course, formed ; and if nitrate of silver be then poured in such a liquor, a precipitate of cyanide of silver is produced, but it is immediately redissolved by shaking, because a double cyanide of silver and of potassium (Ag Cy -4- K Cy) is formed, which dissolves, without alteration, in the excess of potash employed. The addition of a fresh quantity of nitrate of silver produces again a precipitate which agitation causes to disappear as before ; and this reaction goes on until half the amount of prussic acid present in the liquor has been taken up to produce cyanide of silver, the other half being engaged with the potassium in the formation of a double cyanide of silver and of potassium, as just said. As soon, however, as this point is reached, any new quantity of nitrate of silver poured in the liquor causes the cyanide of potassium to react upon the silver of the nitrate, to produce a permanent precipitate of cyanide of silver, which indicates that the reaction is complete, and that the assay is terminated. The presence of chlorides, far from interfering, is desirable, and a certain quantity of common salt is accordingly added, the reaction of chloride of silver being analogous to that of the cyanide of the same metal.

To determine the strength of prussic acid according to the above process, a test or normal solution should be first prepared, which is as follows : —

Since 1 equivalent of nitrate of silver (=170) represents, as we have seen, 2 equivalents of prussic acid (=54), dissolve, therefore, 170 grains of pure fused nitrate of silver in 10,000 water-grains' measure of pure water ; 1,000 water-grains' measure (1 acidimeter full) of such solution will therefore represent 5-4 grains of prussic acid ; and consequently each acidimetrical division 0-054 grain of pure prussic acid.

Take now a given weight or measure of the sample of prussic acid, or cyanide of potas- sium, or laurel, or bitter-almond water, or essence of bitter almonds ; dilute it with three or four times its volume of water, add caustic potash until the whole is rendered alkaline, and carefully pour into it a certain quantity of the normal silver solution from the acidimeter, until a slight precipitate begins to appear which cannot be redissolved by agitation ; observe the number of acidimetrical divisions of the test silver solution employed, and that number multiplied by 0-054 will, of course, indicate the proportion of prussic acid present in the quantity of the sample operated upon.

For such liquids which, like laurel water, contain very little prussic acid, it is advisable to dilute the test silver liquor with nine times its bulk of water ; a decimal solution is thus obtained, each acidimetrical division of which will only represent 0-0054 of prussic acid, by which figure the number of divisions employed should then be multiplied.

As the essence of bitter almonds mixed with water is turbid, it is absolutely necessary to add and shake it with a sufficient quantity of water to dissolve the particles of oil to which the milkiness is due, and render it quite clear.

Instead of an acidimeter, an ordinary balance may be used, as follows : — Take 68 grains of fused nitrate of silver, and dissolve them in 5,937 grains' weight of pure distilled water, making altogether 6,000 grains' weight of test silver solution. Weigh off now in a beaker any quantity, say 100, or, if very weak, 1,000 grains' weight of the sample of prussic acid to be examined, dilute it with three or four times its bulk of water, mix with it a certain quantity of a solution of common salt, and a few drops of caustic potash over and above the quantity necessary to make it alkaline. Pour now carefully into the liquid so prepared a portion of the test solution of silver alluded to, until a turbidness or milkiness begins to be formed, which does not disappear by agitation, and which indicates that the reaction is complete. Every 300 grains of the test silver solution employed represent 1 grain's weight of pure anhydrous prussic acid.

The rationale of these numbers is evident: since 1 equiv. = 170 of nitrate of silver corresponds to 2 equiv. = 54 of prussic acid ; 63 of nitrate of silver correspond to 20 of prussic acid, and consequently 300 of a solution containing 63 of nitrate of silver in 6,000 correspond to 1 of prussic acid, thus : —

170 : 54 :: 63 : 20 6,000 : 20 :: 300 : 1

Lastly, the strength of prussic acid may also be determined with an ordinary balance by a method proposed by Dr. Ure, which method, however, is much less convenient than that of Liebig ; it consists in adding peroxide of mercury, in fine powder, to the liquor which contains prussic acid, until it ceases to be dissolved. As the equivalent of peroxide of mercury = 108, is exactly four times that of prussic acid = 27, the weight of peroxide of mercury employed divided by four will give the quantity of prussic acid present. — A. N.

ACIPENSER. See Isinglass.

ACONITINE. Cco H" NO14. A poisonous alkaloid constituting the active principle of the Aconite, Aconitum Napellus. — C. G. W.

ACORNS. The seed of the oak (quercus). These possess some of the properties of the bark ; but in a very diluted degree. Acorns are now rarely used. Pigs are sometimes fed upon them, 308 bushels were imported in 1855.

ADHESION.

21

ACORTJS CALAMUS. The common sweet flag. This plant is a native of England, growing abundantly in the rivers of Norfolk ; from which county the London market is chiefly supplied. The radix calami aromatici of the shops occurs in flattened pieces about one inch wide, and four or five inches long. It is employed medicinally as an aromatic, and it is said to be used by some distillers to flavor gin. The essential oil {oleum acori calami) of the sweet flag is used by snuff-makers for scenting snuff, and it sometimes enters as one of the aromatic ingredients of aromatic vinegar. — Pereira.

ACROSPIRE." {Plumule, Fr. ; Blattkeim, Germ.) The sprout at the end of seeds ■when they begin to germinate. The name is derived from two Greek words, signifying highest and spire, and has been adopted on account of its spiral form. It is the plume or plumule of modern botanists. Malsters use the name to express the growing of the barley. " The first leaves that appear when corn sprouts." — Lindley.

ACRYLAMINE or ALLYLAMNE. (Cf H7 N.) A new alkaloid obtained by Hoff- mann and Cahorns, by boiling cyanate of allyle with a strong solution of potash. It boils at about 363°.— C. G. TV".

ACTINISM. (From o.kt\v, a ray ; signifying merely the power of a ray, without defining what character of ray is intended.)

As early as 1812, M. Berard (in a communication to the Academy of Sciences, on some observations made by him of the phenomena of solar action) drew attention to the fact that three very distinct sets of physical powers were manifested. Luminous power, Heat-produc- ing power, and Chemical power.

The actual conditions of the sun-beam will be understood by reference to the annexed woodcut, and attention to the following description, fig. 4: a b represents the prismatic spectrum — as obtained by the decomposition of white

light by the prism — or Newtonian luminous spectrum, 4 5

consisting of certain bands of color. Newton deter- mined those rays to be seven in number ; red, orange, yellow, green, blue, indigo, and violet ; recent re- searches, by Sir John Herschel and others, have proved the existence of two other rays ; one, the extreme red or crimson ray e, found at the least refrangible end of the spectrum, the other occurring at the most frangible end, or beyond the violet rays, which is a lavender or gray ray. Beyond this point up to/, Professor Stokes has discovered a new set of rays, which are only brought into view when the light is received upon the surfaces of bodies which possess the property of altering the refrangibility of the rays. Those rays have been called the fluorescent rays, from the circumstance that some of the varieties of Fluor Spar exhibit this phenomenon in a remarkable manner. In the engraving {fig. 4,) the curved line l from a to c indicates the full extent of the luminous spectrum, the point marked l showing the maximum of illuminating power, which exists in the yellow ray.

Sir William Herschel and Sir Henry Englefield de- termined, in the first instance, the maximum point for the calorific rays, and Sir John Herschel subsequently confirmed their results, proving that the greatest heat was found below the red ray, and that it gradually diminished in power with the increase of refrangibility in the rays, ceasing entirely in the violet ray. Heat rays have been detected down to the point d, and the curved line h indicates the extent of their action.

Now, if any substance capable of undergoing chemical change be exposed to this spec- trum, the result will be found to be such as is represented in the accompanying figure and fig. 5. Over the space upon which the greatest amount of light falls, i. e. the region of the yellow and orange rays l, no chemical change is effected : by prolonged action a slight change is brought about where the red ray falls, r, but from the mean green ray g up to the point /, a certain amount of chemical action is maintained ; the maximum of action being in the blue and violet rays a. Thus the curve line {fig. 4) from e to/ represents the extent and degree of chemical power as manifested in the solar spectrum. Two maxima are marked a a, differing widely however in their degree.

ADHESION {sticking together). The union of two surfaces. "With the phenomena which are dependent upon bringing two surfaces so closely together that the influence of cohesion is exerted, we have not to deal. In arts and manufactures, adhesion is effected by interposing between the surfaces to be united, some body possessing peculiar properties,

22

ADIPOSE SUBSTANCE oe ADIPOSE TISSUE.

such as gum, plaster, resin, inarine or ordinary glue, and various kinds of cement. (See those articles.} In many treatises, there has been a sad confusion between the terms adhesion and cohesion. It is to be regretted that our literature shows a growing careless- ness in this respect. Adhesion should be restricted to mean, sticking together by means of some interposed substance ; cohesion, the state of union effected by natural attraction.

Not only is adhesion exhibited in works of art or manufacture, we find it very strikingly exhibited in nature. Fragments of rocks which have been shattered by convulsion are found to be cemented together by silica, lime, oxide of iron, and the like. We sometimes find portions of stone cemented together by the ores of the metals ; and, again, broken parts of mineral lodes are frequently reunited by the earthy minerals.

ADIPOSE SUBSTANCE or ADIPOSE TISSUE. (Tissu graisseux, Fr.) An animal oil, resembling in its essential properties the vegetable oils. During life, it appears to exist in a fluid or semi-fluid state ; but in the dead animal, it is frequently found in a solid form, constituting suet, which, when divested of the membrane in which it is contained, is called tallow. See Tallotv, Oils, &c.

ADIT or ADIT LEVEL. The horizontal entrance to a mine ; a passage or level driven, into the hill-side. The accompanying section gives, for the purpose of distinctness,

an exaggerated section of a portion of the subterranean workings of a metal- liferous mine. It should be understood that d represents a mineral lode, upon which the shaft, a, has been sunk. At a certain depth from the surface of the hill the miners would be inconvenienced by water, consequently a level is driven in from the side of the hill, 5, through which the wat£r flows off, and through which also the miner can bring out the broken rock, or any ores which he may obtain. Proceeding still deeper, sup- posing the workings to have com- menced, as is commonly the case, at a certain elevation above the sea-level, similar conditions to those described again arising, another level is driven so as to intersect the shaft or shafts, as shown at c. In this case, b would be called the shallow, and c the deep adit. The economy of such works as these is great, saving the cost of expensive pumping machinery, and, in many cases, saving also considerable labor in the removal of ores or other matter from the mine.

ADZE. A cutting instrument ; differing from the axe by the edge being placed at nearly right angles to the handle, and being slightly curved up or inflected towards it. The instrument is held in both hands, whilst the operator stands upon his work in a stooping position ; the handle being from twenty-four to thirty inches long, and the weight of the blade from two to four pounds. The adze is swung in a circular path almost of the same curvature as the blade, the shoulder-joint being the centre of motion, and the entire arm and tool forming, as it were, one inflexible radius ; the tool, therefore, makes a succession of small arcs, and in each blow the arm of the workman is brought in contact with the thigh, which serves as a stop to prevent accident. In coarse preparatory works, the work- man directs his adze through the space between his two feet ; he thus surprises us by the quantity of wood removed ; in fine works he frequently places his toes over the spot to be wrought, and the adze penetrates two or three inches beneath the sole of the shoe ; and he thus surprises us by the apparent danger, yet perfect working of the instrument, which, in the hands of a shipwright in particular, almost rivals the joiner's plane ; it is with him the nearly universal paring instrument, and is used upon works in all positions. — Holtzapffel.

AERATED WATER. The common commercial name of water artificially impregnated with carbonic acid.

AEROLITES. Meteoric stones. It cannot be denied that masses of solid matter have fallen from the atmosphere upon the earth.

It is evident that meteoric stones are of cosmical origin ; and the composition, there- fore, of such as have been examined, shows us the composition of masses of matter exist- ing beyond the earth. A few analyses of meteoric stones will exhibit the chemical charac- ter of these extraordinary masses.

(2) (3) (4)

90-88 . . 88-98 . . 86-64

8-45 . . 10-35 . . 13-04

0-65 . . . .

0-02 . . 0-21 . . 0-27

. . 0-34 . .

. . 0-10 . . 0-05

— Brook and Miller.

Iron,

Nickel,

Cobalt,

Copper,

Tin,

Phosphorus,

(1)

8-88 0-66

AIR. 23

A meteorite fell at Dharwar, in the East Indies, on the 15th of February, 1848, which gave 5S-3 per cent, of silicates insoluble in aqua regia ; 2'5 of sulphur, 6-Y6 of nickel, and 22.18-of iron. Another stone from Singhur, near Ponna, in the Deccan, gave earthly sili- cate, 19"5 ; iron, 69-16 ; and nickel, 4-24. Ehrenberg examined a black inky rain-water which fell in Ireland on the loth of April, 1S-19, and found the black color to consist of minute particles of decayed plants, which had probably been brought by the trade winds, and, floating in clouds of aqueous vapor, had decayed.

AEROSTATION; AERONAUTICS. The ascent into the atmosphere by means of balloons. See Balloons.

AGARIC of the oak ; called also surgeon's agaric, spunk, touchivood. A fungus found growing on the oak, birch, willow, and other trees. See Amadou.

AGATE. An instrument used by gold-wire drawers, so called from the agate fixed in the middle of it.

AGATE. (Agate, Fr. ; Achat, Gr. ;■ Achates, Lat.) A siliceous mineral ; a varie- gated variety of chalcedon}-.

This stone is the 'Axdrns of the Greeks, by whom it was so called after the river in Sicily of that name, whence, according to Theophrastus, agates were first procured. Bo- chart, with much probability, deduces the name from the Punic and Hebrew, nakad, spotted.

The colors of agate are either arranged in parallel or concentric bands, or assume the form of clouds or spots, or arborescent and moss-like stains. These colors are due to the presence of metallic oxides, and when indistinct, they are frequently artificially developed or produced. By boiling the colorless stone in oil, and afterwards in sulphuric acid, the oil is absorbed by the more porous layers of the stone ; it Subsequently becomes carbonized, and thus the contrast of the various colors is heightened. The red varieties, also, are arti- ficially produced by boiling them in a solution of proto-sulphate of iron ; after which, upon exposing the stones to heat, peroxide of iron is formed, and thus red bands, or rings, of varying intensities, are produced. Cornelians are thus very commonly formed ; the color- ing matter of the true stone being a peroxide of iron.

Agates never occur in a crystalline form, but in the form of rounded pebbles ; they are translucent by transmitted light, but are not transparent, have a wax-like fracture, and they are susceptible of a brilliant polish. Agates are used in the arts for inlaying, and for bur- nishing gold and silver : they are also made into mortars for chemical purposes ; and when cut and polished, they are converted, in considerable quantities, into brooches, bracelets, and other ornamental articles. Agates are brought to this country from Arabia, India, and Oberstein, in Saxony : they are also found in Perthshire, and other parts of Scotland. The Scotch Pebble is a variety of the agate, known by its zig-zag pattern as the Fortification Agate. Agates are found frequently in the amygdaloid rocks of Galgenburg, near Ober- stein. They are usually ground into form, cut, and polished, at water-mills in the neigh- borhood, where a considerable trade in them is carried on. Moss Agate, or Mocha Stone, is a chalcedony, containing within it dendritic or moss-like delineations, of an opaque brownish-yellow color, which are due to oxide of manganese, or of iron. — H. W. B.

Agates are found in the Canton markets, as articles of commerce, in abundance, and of the following varieties : — The white-veined agate, called also Mocha Stone, varies from 1 to 8 inches in diameter. The dull, milky agate, not so valuable, occurs in sizes of 1 to 10 inches. Lead-colored agate, sometimes uniform, and sometimes spotted, occurs of large size, and is used for cups and boxes. Flesh-colored. Blood-colored. This is sometimes variegated with pale blue and brown ; the blue always surrounds the red ; the brown has the tint of horn. Clouded and spotted flesh-colored agate is found subject to many flaws. Red agate, with yellow, is of 1 to 4 inches in diameter. The yellow has various tints. Sometimes the pebbles are 7 inches in length. The yellow agate is used for knife-handles. The pale yellow agate is very scarce ; it is called also Leonina, being variegated with white, black, and green, and bearing some resemblance to a lion's skin. Blackish-veined brown agate, in pieces from 2 to 7 inches in diameter, is very hard, and is cut into seals, buttons, and heads of canes, &c, with natural veins, or fictitious colors, sunk into the stone. It appears to be of much value. — Oriental Commerce.

Agate is found sufficiently large to be formed into mortars for chemical purposes. " The royal collection at Dresden contains a table-service of German agate ; and at Vienna, in the Imperial cabinet, there is an oval dish, twenty-two inches in length, formed of a single stone." — Dana..

Agates may be stained artificially by soaking in a solution of nitrate of silver, and after- wards exposing them to the sun. These artificial colors disappear on laying the stone for a night in aquafortis. A knowledge of the practicability of thus staining agates naturally leads to the suspicion of many of the colors being the work, not of nature, but of art.

AIR. The gaseous envelope which surrounds this Earth is emphatically so called ; it consists of the gases nitrogen and oxygen.

About 79 measures of nitrogen, or azote, and 21 of oxygen, with T J6th of carbonic acid,

24

AIE-ENGINE.

constitute the air we breathe. The term air is applied to any permanently gaseous body. And we express different conditions of the air, as good air, bad air, foul air, &e.

AIR-ENGINE. The considerable expansibility of air by heat naturally suggested its use as a motive power long before theoretical investigation demonstrated its actual value. The great advance made during the few last years in our knowledge of the mechanical action of heat, has enabled us to determine with certainty the practical result which may be obtained by the use of any contrivance for employing heat as a prime mover of machinery. We are indebted to Professor Wm. ' Thomson for the fundamental theorem which decides the economy of any thermo-dynamic engine. It is — that in any perfectly constructed engine the fraction of heat converted into work is equal to the range of temperature from the highest to the lowest point, divided by the highest temperature reckoned from the zero of absolute temperature. Thus, if we have a perfect engine in which the highest temperature

980—80

is 280° and the lowest 80° F., the fraction of heat converted into force will be i.

280-J-460, or rather more than one quarter. So that, if we use a coal of which one pound in combus- tion gives out heat equivalent to 10,380,000 foot pounds, such an engine as we have just described would produce work equal to 2,805,405 foot pounds for each pound of coal consumed in the furnace. From the above formula of Professor Thomson, it will appear that the economy of any perfect thermo-dynamic engine depends upon the range of tem- perature we can obtain in it. And as the lowest temperature is generally nearly constant, being ruled by the temperature of the surface of the earth, it follows that the higher we can raise the highest temperature, the more economical will be the engine. The question is thus reduced to this : — In what class of engine can we practically use the highest tempera- ture ? In the steam-engine worked with saturated vapor, the limit is obviously deter- mined by the amount of pressure which can be safely employed. In the steam-engine worked with super-heated vapor — i. e. in which the vapor, after passing from the boiler, receives an additional charge of heat without i)eing allowed to take up more water — and also in the air-engine, the limit will depend upon the temperature at which steam or air acts chemically upon the metals employed, as well as upon the power of the metals themselves to resist the destructive action of heat. It thus appears that the steam-engine worked with superheated steam possesses most of the economical advantages of the air-engine. But when we consider that an air-engine may be made available where a plentiful supply of water cannot be readily obtained, the importance of this kind of thermo-dynamic engine is incontestable. The merit of first constructing a practical air-engine belongs to Mr. Stirling. Mr. Ericsson has subsequently introduced various refinements, such as the respirator — a reticulated mass of metal, which, by its extensive conducting surface, is able, almost instan- taneously, to give its own temperature to the air which passes through it. But various practical difficulties attend these refinements, which, at best, only apply to engines worked between particular temperatures. The least complex engine, and that which would probably prove most effectual in practice, is that described in the "Philosophical Transactions," 1852, Part I. It consists of a pump, which compresses air into a receiver, in which it receives an additional charge of heat ; and a cylinder, the piston of which is worked by the heated air as it escapes. The difference between the work produced by the cylinder and that absorbed by the pump constitutes the force of the engine ; which, being compared with the heat communicated to the receiver, gives results exactly conformable with the law of Professor Thomson above described. — J. P. J.

Dr. Joule has proposed various engines to be worked at temperatures below redness, which, if no loss occurred by friction or radiation, would realize about one-half the work due to the heat of combustion ; or about four times the economical duty which has, as yet, been attained by the most perfect steam-engine.

A detailed account of Ericsson's Calorific Engine may be useful, especially as a certain amount of success has attended his efforts in applying the expansive power of heat to move machinery. It is stated in Hunt's " Merchant's Magazine" that Ericsson's engines are at work in the foundry of Messrs. Hogg and Delamater, in New York ; one engine being of five and another of sixty-horse power. The latter has four cylinders. Two, of seventy-two inches in diameter, stand side by side. Over each of these is placed one much smaller. Within these are pistons exactly fitting their respective cylinders, and so connected, that those within the lower and upper cylinders move together. Under the bottom of each of the lower cylinders a fire is applied, no other furnaces being employed. Neither boilers nor water are used. The lower is called the working cylinder ; the upper, the supply cylinder. As the piston in the supply cylinder moves down, valves placed in its top, open, and it becomes filled with cold air. As the piston rises within it, these valves close, and the air within, unable to escape as it came, passes through another set of valves into a receiver, from whence it has to pass into the working cylinder to force up the working piston within it. As it leaves the receiver to perform this duty, it passes through what is called the regenerator, where it becomes heated to about 450° ; and upon entering the working cylin- der, it is further heated by the supply underneath. For the sake of illustration, merely, let

ALABASTER. 25

us suppose that the working cylinder contains double the area of the supply cylinder : the cold air which entered the upper cylinder will, therefore, but only half fill the lower one. In the course of its passage to the latter, however, it passes through the regenerator ; and as it enters the working cylinder, we will suppose that it has become heated to about 480°, bv which it is expanded to double its volume, and with this increased capacity it enters the workino- cylinder. We will further suppose the area of the piston within this cylinder to contain 1,000 square inches, and the area of the piston in the supply cylinder above to contain but 500. The air presses upon this with a mean force, we will suppose, of about eleven pounds to, each square inch; or, in other words, with a weight of 5,500 pounds. Upon the surface of the lower piston the heated air is, however, pressing upwards with a like force upon each of its 1,000 square inches ; or, in other words, with a force which, after overcoming the weight above, leaves a surplus of 5,500 pounds, if we make no allow- ance for friction. This surplus furnishes the working power of the engine. It will be seen that after one stroke of its piston is made, it will continue to work with this force so long as sufficient heat is supplied to expand the air in the working cylinder to the extent stated ; for, so long as the area of the lower piston is greater than that of the upper and a like pressure is upon every square inch of each, so long will the greater piston push forward the smaller, as a two-pound weight upon one end of a balance will be sure to bear down a one- pound weight placed on the other. We need hardly say, that after the air in the working cylinder has forced up the piston within it, a valve opens ; and as it passes out, the pistons, by the force of gravity, descend, and cold air again rushes into and fills the supply cylinder. In this manner the "two cylinders are alternately supplied and discharged, causing the pistons in each to play up and down substantially as they do in the steam-engine.

The regenerator must now be described. It has been stated that atmospheric air is first drawn into the supply cylinder, and that it passes through the regenerator into the working cylinder. The regenerator is composed of wire net, like that used in the manufacture of sieves, placed side by side, until the series attains a thickness of about 12 inches. Through the almost innumerable cells formed by the intersections of the wire, the air must pass on its way to the working cylinder. In passing through these it is so minutely divided that all parts are brought into contact with the wires. Supposing the side of the regenerator nearest the working cylinder is heated to a high temperature, the air, in passing through it, takes up, as we have said, about 450° of the 480° of heat required to double the volume of the air ; the additional 30° are communicated by the fire beneath the cylinder.

The air has thus become expanded, it forces the piston upwards ; it has done its work — valves open, and the imprisoned air, heated to 480°, passes from the cylinder and again enters the regenerator, through which it must pass before leaving the machine. It has been said that the side of this instrument nearest the cylinder is kept hot ; the other side is kept cool by the action upon it of the air entering in the opposite direction at each up-stroke of the pistons ; consequently, as the air fr,om the working cylinder passes out, the wires absorb the heat so effectually, that when it leaves the regenerator it has been robbed of it all, except about 30°.

The regenerator in the 60-horse engine measures 26 inches in height and width, inter- nally. Each disk of wire composing it contains 6*76 superficial inches, and the net has 10 meshes to the inch. Each superficial inch, therefore, contains 100 meshes, which, multiplied by 676, gives 67,6<J8 meshes in each disk ; and, as 200 disks are employed, it follows that the regenerator contains 13,520,000 meshes; and consequently, as there are as many spaces between the disks as there are meshes, we find that the air within it is distributed in about 27,000,000 minute cells. Thence every particle of air, in passing through the regen- erator, is brought into very close contact with a surface of metal which heats and cools it alternately. Upon this action of the regenerator, Ericsson's Calorific Engine depends. In its application on the large scale, contemplated in the great Atlantic steamer called the " Ericsson," the result was not satisfactory. We may, however, notwithstanding this result safely predicate, from the investigation of Messrs. Thomson and Joule, that the expansion of air by heat will eventually, in some conditions, take the place of steam as a motive power.

AIR-GUN". This is a weapon in which the elastic force of air is made use of to project the ball. It is so arranged, that in a cavity in the stock of the gun, air can be, by means of a piston, powerfully condensed. Here is a reserved force, which, upon its being relieved from pressure, is at once exerted. When air has been condensed to about J5 of its bulk, it exerts a force which is still very inferior to that of gunpowder. In many other respects the air-gun is but an imperfect weapon, consequently it is rarely employed.

AIRO-HYDROGEN BLOWPIPE. A blowpipe in which air is used in the place of oxygen, to combine with and give intensity of heat to a hydrogen flame for the purposes of soldering. See Autogenous Soldering.

ALABASTER, Gypsum, Plaster of Paris (Albdtre, Fr. ; Alabaster, Germ.), a sulphate of lime. (See Alabaster, Oriental.) When massive, it is called indifferently alabaster or gypsum ; and when in distinct and separate crystals, it is termed sclenite. Massive alabas-

26

ALABASTER, ORIENTAL.

ter occurs in Britain in the new red or keuper marl : in Glamorganshire, on the Bristol Channel ; in Leicestershire, at Syston ; at Tutbury and near Burton-on-Trent, in Stafford- shire ; at Chellaston, in Derbyshire ; near Droitwich it is associated in the marl with rock salt, in strata respectively 40 and 75 feet in thickness ; and at Northwich and elsewhere the red marl is intersected with frequent veins of gypsum. At Tutbury it is quarried in the open air, and at Chellaston in caverns, where it is blasted by gunpowder ; at both places it is burned in kilns, and otherwise prepared for the market. It lies in irregular beds in the marl, that at Chellaston being about 30 feet thick. There is, however, reason to suppose that it was not originally deposited along with the marl as sulphate of lime, but rather that calcareous strata, by the access of sulphuric acid and water, have been converted into sul- phate of lime, — a circumstance quite consistent with the bulging of the beds of marl with which the gypsum is associated, the lime, as a sulphate, occupying more space than it did in its original state as a carbonate. At Tutbury and elsewhere, though it lies on a given general horizon, yet it can scarcely be said to be truly bedded, but ramifies among the beds and joints of the marl in numerous films, veins, and layers of fibrous gypsum.

A snow-white alabaster occurs at Volterra, in Tuscany, much used in works of art in Florence and Leghorn. In the Paris basin it occurs as a granular crystalline rock, in the Lower Tertiary rocks, known to geologists as the upper part of the Middle Eocene fresh- water strata. It is associated with beds of white and green marls ; but in the Thuringewald there is a great mass of sulphate of lime in the Permian strata. It has been sunk through to a depth of 10 feet, and is believed to be metamorphosed magnesian limestone or Zech- stein. In the United States this calcareous salt occurs in numerous lenticular masses in marly and sand strata, of that part of the Upper Silurian strata known as the Onondaga salt group. It is excavated for agricultural purposes. For mineralogical character, &c, see Gypsum.— A. C. R.

The gypsum of our own country is found, in apparently inexhaustible quantities, in the red marl formation in the neighborhood of Derby, and has been worked for many centuries. The great bulk of it is used for making plaster of Paris, and as a manure ; and it is the basis of many kinds of cements, patented — as Keene's, Martin's, and others.

To get it for these purposes, it is worked by mining underground, and the stone is blasted by gunpowder ; but this shakes it so much as to be unfit for working into orna- ments, &c. ; to procure blocks for which it is necessary to have an open quarry. By removing the superincumbent marl, and laying bare a large surface of the rock, the alabaster being very irregular in form, and jutting out in several parts, allows of its being sawn out in blocks of considerable size, and comparatively sound, (as is illustrated by the large tazza in the Museum of Practical Geology.) This stone, when protected from the action of water, is extremely durable, as may be seen in churches all over the country, where monumental effigies, many centuries old, are now as perfect as the day they were made, excepting, of course, wilful injuries ; but exposure to rain soon decomposes the stone, and it must be borne in mind that it is perfectly unsuited for garden vases or other out-door work in this country.

In working, it can be sawn up into slabs with toothed saws, and for working mouldings and sculptures, fine chisels, rasps, and files are the implements used ; the polishing is per- formed by rubbing it with pieces of sandstone, of various degrees of fineness, and water, until it is quite free from scratches, and then giving a gloss by means of polishing powder (oxide of tin) applied on a piece of cloth, and rubbed with a considerable degree of friction on the stone. This material gives employment in Derby to a good many hands in forming it into useful and ornamental articles, and is commonly called Derbyshire Spar ; most of the articles are turned in the lathe, and it works something like very hard wood.

Another kind of gypsum also found in Derbyshire is the fibrous or silky kind ; it occurs in thin beds, from one to six inches in depth, and is crystallized in long needle-like fibres ; being easily worked, susceptible of a high polish, and quite lustrous, it is used for making necklaces, bracelets, brooches, and such like small articles. — S. H.

ALABASTER, ORIENTAL. Oriental alabaster is a form of stalagmitic or stalactitic carbonate of lime, an Egyptian variety of which is highly esteemed. ■« It is also procured from the Pyrenees, from Chili, and from parts of the United States of America. Ancient quarries are still in existence in the province of Oran, in Algeria.

ALBATA PLATE, a name given to one of the varieties of white metal now so com- monly employed. See Copper, and Allots.

ALBUM GRJ5CUM. The white faeces of dogs. After the hair has been removed from skins, this is used to preserve the softness of them, and prepare them for the tan-pit. Fowls' dung is considered by practical tanners as superior to the dung of dogs, and this is obtained. as largely as possible. These excreta may be said to be essentially phosphate of lime and mucus. We are informed that various artificial compounds which represent, chemically, the conditions of those natural ones, have been tried without producing the same good results. It is a reflection on our science, if this is really the ease.

ALBUMEN. (Album Ovi.) Albumen is a substance which forms a constituent part

ALCOHOL. 27

of the animal fluids and solids, and which is also found in the vegetable kingdom. It exists nearly pure in the white of egg. Albumen consists of—

Carbon, 53-32

Hydrogen, ...... 7'29

Nitrogen, ....... 15'7

Sulphur, . . . • ■ • 1*3

Oxygen, ....... 22'39

Its Formula being S2 N27 C210 Hi(ra O68. Albumen coagulates by heat, as is illustrated in the boiling of an°egg. The salts of tin, bismuth, #lead, silver, and mercury form with albumen white insoluble precipitates; therefore, in* cases of poisoning by corrosive sub- limate, nitrate of silver, or sugar of lead, the white of egg is the best antidote which can be administered.

Albumen is employed in Photography, which see.

"We imported the following quantities of albumen: — in 1835, 275 cwts. ; in 1856, 382 cwts.

ALCOHOL. (Alcool, Fr. ; Alkohol, or Weingeist, Germ.) The word alcohol is de- rived from the Hebrew word " kohol," "pns to paint. The oriental females were and are still in the habit of painting the eyebrows with various pigments ; the one generally em- ployed was a preparation of antimony, and to this the term was generally applied. It became, however, gradually extended to all substances used for the purpose, and ultimately to strong spirits, which were employed, probably, as solvents for certain coloring principles. The term was subsequently exclusively used to designate ardent spirits, and ultimately the radical or principle upon which their strength depends.

As chemistry advanced, alcohol^ was found to be a member only of a class of bodies agreeing with it in general characters ; and hence the term is now generic, and we speak of the various alcohols. Of these, common or vinous alcohol is the best known ; and, in common life, by " alcoholic liquors," we invariably mean those containing the original or vinous alcohol. '

When the characters of ordinary alcohol have been stated, allusion will be made to the class of bodies of whk;h this is the type.

Fermented liquors were known in the most remote ages of antiquity. We read (Gene- sis ix.) that after the flood " Noah planted a vineyard, and he drank of the wine and was drunken." Homer, who certainly lived 900 years before the Christian era, also frequently mentions wine, and notices its effects on the body and mind (Odyssey IX. and XXI.) ; and Herodotus tells us that the Egyptians drank a liquor fermented from barley. The period when fermented liquors were submitted to distillation, so as to obtain " ardent spirits" is shrouded in much obscurity. Raymond Lully* was acquainted with " spirits of wine," which he called aqua ardens. The separation of absolute alcohol would appear to have been first effected about this period (1300), by Arnauld de Villeneuve, a celebrated physician residing in Montpellier (Gerhardt), and its analysis was first performed by Th. de Saussure.f

The preparation of alcohol may be divided into three stages : —

1. The production of a fermented vinous liquor — the Fermentation.

2. The preparation from this of an ardent spirit — the Distillation.

3. The separation from this ardent spirit of the last traces of water — the Rectification. 1. Fermentation. The term "fermentation" is now applied to those mysterious

changes which vegetable (and animal) substances undergo when exposed, at a certain tem- perature, to contact with organic or even organized bodies in a state of change.

There are several bodies which suffer these metamorphoses, and under the influence of a great number of different exciting substances, which are termed the " ferments ;" more- over, the resulting products depend greatly upon the temperature at which the change takes place.

The earliest known and best studied of these processes is the one commonly recognized as the vinous or alcoholic fermentation.

In this process solutions containing sugar — either the juice of the grape (see Wine) or an infusion of germinated barley, malt, (see Beer) — are mixed with a suitable quantity of a ferment ; beer or wine yeast is usually employed (see Yeast), and the whole maintained at a temperature of between 70° and 80° F. (21° to 26° C.)

Other bodies in a state of putrefactive decomposition will effect the same result as the yeast, such as putrid blood, white of egg, &c.

The liquid swells up, a considerable quantity of froth collects on the surface, and an abundance of gas is disengaged, which is ordinary carbonic acid (CO2). The composition of (pure) alcohol is expressed by the formula C4 H° O2, and it is produced in this process

* Thomson's History of Chemistry, i. 41. (1830.) t Annalcs do Chimic, xlii. '225.

28

ALCOHOL.

by the breaking up of an equivalent of grape sugar, C'4 H2e O21 hoi, 8 of carbonic acid, and 4 of water —

into 4 equivalents of alco-

24 TTMI fV28

O8 = 4 (C4 H6 02)

H4

II4

4 HO

C

Ole = 8 CO2

It is invariably the grape sugar which undergoes this change ; if the solution contains cane sugar, the cane sugar is first converted into grape sugar under the influence of the ferment. See Sugar.

Much diversity of opinion exists with respect to the office which the ferment performs in this process, since it does not itself yield any of the products. See Fermentation.

The liquid obtained by the vinous fermentation has received different names, according to the source whence the saccharine solution was derived. When procured from the ex- pressed juice of fruits — such as grapes, currants, gooseberries, &c. — the product is denomi- nated wine ; from a decoction of malt, ale or beer ; from a mixture of honey and water, mead; from apples, cider ; from the leaves and small branches of the spruce-fir (abies excelsa, &c), together with sugar or treacle, spruce ; from rice, rice beer (which yields the spirit arrack) ; from cocoa-nut juice, palm wine.

It is an interesting fact that alcohol is produced in very considerable quantities (in the aggregate) during the raising of bread. The carbonic acid which is generated in the dough, and which during its expulsion raises the bread, is one of the products of the fermentation of the sugar in the flour, under the influence of the yeast added ; and of course at the same time the complementary product, alcohol, is generated. As Messrs. Ronalds and Richai'dson remark :* " The enormous amount of bread that is baked in large towns — in London, for instance, 8.8 millions of cwts. yearly — would render the small amount of alcohol contained in it of sufficient importance to be worth collecting, provided this could be done sufficiently cheaply." In London it has been estimated that in this way about 300,000 gallons of spirits are annually lost ; but the cost of collecting it would far exceed its value.

2. Distillation. By the process of distillation, ardent spirits are obtained, which have likewise received different names according to the sources whence the fermented liquor has been derived : viz. that produced by the distillation of wine being called brandy, and in France cognac, or eau de vie ; that produced by the distillation of the fermented liquor from sugar and molasses, rum. There are several varieties of spirits made from the fer- mented liquor procured from the cereals (and especially barley), known according to their peculiar methods of manufacture, flavor, &c. — as whiskey, gin, Hollands — the various compounds and liqueurs. In India, the spirit obtained from a fermented infusion of rice is called arrack.

3. Rectification ;. preparation of absolute alcohol. It is impossible by distillation alone to deprive spirit of the whole of the water and other impurities — to obtain, in fact, pure or absolute alcohol.

This is effected by mixing with the liquid obtained after one or two distillations, certain bodies which have a powerful attraction for water. The agents commonly employed for this purpose are quicklime, carbonate of potash, anhydrous sulphate of copper, or chloride of calcium. Perhaps the best adapted for the purpose, especially where large quantities are required, is quicklime ; it is powdered, mixed in the retort with the spirit (previously twice distilled), and the neck of the retort being securely closed, the whole left for 24 hours, occasionally shaking ; during this period the lime combines with the water, and then on carefully distilling, avoiding to continue the process until the last portions come over, an alcohol is obtained which is free from water. If not quite free, the same process may be again repeated.

In experiments on a small scale, an ordinary glass retort may be employed, heated by a water-bath, and fitted to a Liebig's condenser cooled by ice-water, which passes lastly into a glass receiver, similarly cooled.

Although alcohol of sufficient purity for most practical purposes can be readily ob- tained, yet the task of procuring absolute alcohol entirely free from a trace of water, is by no means an easy one.

Mr. Drinkwater f effected this by digesting ordinary alcohol of specific gravity .850 at 60° F. for 24 hours with carbonate of potash previously exposed to a red heat ; the alcohol was then carefully poured off and mixed in a retort with as much fresh-burnt quicklime as was sufficient to absorb the whole of the alcohol ; after digesting for 48 hours, it was slowly

* Chemical Technology, by Dr. F. Knapp : edited hy Messrs. Eonalds and Richardson. Vol. iii. 108. t On the Preparation of Absolute Alcohol, and the Composition of Proof Spirit. See Memoirs of the Chemical Society, vol. iii. p. 447.

ALCOHOL. 29

distilled in a water-bath at a temperature of about 180° F. This alcohol was carefully re- distilled, and its specific gravity at 60° F. found to be -7947, which closely agrees with that given by Gay-Lussae as the specific gravity of absolute alcohol. He found, moreover, that recently ignited anhydrous sulphate of copper was a less efficient dehydrating agent than quicklime.

Graham recommends that the quantity of lime employed should never exceed three times the weight of the alcohol.

Chloride of calcium is not so well adapted for the purification of alcohol, since the alcohol forms a compound with this salt.

Many other processes have been suggested for depriving alcohol of its water.

A curious process was proposed many years ago by Soemmering,* which is dependent upon the peculiar fact, that whilst water moistens animal tissues, alcohol does not, but tends rather to abstract water from them. If a mixture of alcohol and water be enclosed in an ox bladder, the water gradually traverses the membrane and evaporates, whilst the alcohol does not, and consequently by the loss of water the spirituous solution becomes con- " centrated.

This process, though an interesting illustration of exosmose, is not practically applicable to the production of anhydrous alcohol ; it is, however, an economical method, and well suited for obtaining alcohol for the preparation of varnishes. Smugglers, who bring spirits into France in bladders hid about their persons, have long known, that although the liquor decreased in bulk, yet it increased in strength ; hence the people preferred the article con- veyed clandestinely. Prof. Graham has ingeniously proposed to concentrate alcohol as follows :

" A large shallow basin is covered, to a small depth, with recently burnt quicklime, in coarse powder, and a smaller basin, containing three or four ounces of commercial alcohol, is made to rest upon the lime ; the whole is placed under the low receiver of an air-pump, and the exhaustion continued till the alcohol evinces signs of ebullition. Of the mingled vapors of alcohol and water which now fill the receiver, the quicklime is capable of uniting with the aqueous only, which is therefore rapidly withdrawn, while the alcohol vapor is un- affected ; and as water cannot remain in the alcohol as long as the superincumbent atmos- phere is devoid of moisture, more aqueous vapor rises, which is likewise abstracted by the lime, and thus the process goes on till the whole of the water in the alcohol is removed. Several days are always required for this purpose.

Properties of Alcohol. — Absolute.

In the state of purity, alcohol is a colorless liquid, highly inflammable, burning with a pale blue flame, very volatile, and having a density of 0792 at 15-5° C. (60° F.) {Drink- water.) It boils at 78-4° C. (173° F.) It has never yet been solidified, and the density of its vapor is 1'6133.

Anhydrous alcohol is composed by weight of 5248 carbon, 13-04 hydrogen, and 34-78 of oxygen. It has for its symbol C4 H6 0'- = C* H5 0 4- HO, or hydrated oxide of ethyle. It has a powerful affinity for water, removing the water from moist substances with which it is brought in contact. In consequence of this property, it attracts water from the air, and rapidly becomes weaker, unless kept in very well-stopped vessels. In virtue of its attraction for water, alcohol is very valuable for the preservation of organic substances, and especially of anatomical preparations, in consequence of its causing the coagulation of albuminous substances ; and for the same reason it causes death when injected into the veins.

When mixed with water a considerable amount of heat is evolved, and a remarkable contraction of volume is observed ; these effects being greatest with 54 per cent, of alco- hol and 46 of water, and thence decreasing with a greater proportion of water. For alco- hol which contains 90 per cent, of water, this condensation amounts to 1-94 per cent, of the volume ; for 80 per cent, 2-87 ; for 70 per cent., 3-44 ; for 60 per cent., 3'73 ; for 40 per cent., 344 ; for 30 per cent, 2-72 ; for 20 per cent, 1-72 ; for 10 per cent, 0-72.

Alcohol is prepared absolute for certain purposes, but the mixtures of alcohol and water commonly met with in commerce are of an inferior strength. Those commonly sold are "Rectified Spirit,'' and "Proof Spirit"

"Proof Spirit" is defined by Act of Parliament, 58 Geo. III. c. 28, to be "such as shall, at the temperature of fifty-one degrees of Fahrenheit's thermometer, weigh exactly twelve-thirteenth parts of an equal measure of distilled water." And by very careful experi- ment, Mr. Drinkwater has determined that this proof spirit has the following composition: —

Alcohol and Water.	Specific Gravity at CO1 F.	Bulk of the mixture of 100 measures of Alcohol, and 81-82 of Water.
By weight.	By measure.
Alcohol. "Water. 100 + 103-09 49-100 -f 50-76	Alcohol. -Water. 100 -4- 81-82	•919.	175-25

* Soemmering. "Denkschriften d. K. Akad. d. Wissenchaften zu Miinschen," ITU to 1S24.

30

ALCOHOL.

Spirit which is weaker is called "under proof;" and that stronger, "above proof." The origin of these terms is as follows : — Formerly a very rude mode of ascertaining the strength of spirits was practised, called the proof ; the spirit was poured upon gunpowder and inflamed. If, at the end of the combustion, the gunpowder took fire, the spirit was said to be above or over proof. But if the spirit contained much water, the powder was rendered so moist that it did not take fire : in which case the spirit was said to be under or below proof.

Rectified spirit contains from 54 to 64 per cent, of absolute alcohol ; and its specific gravity is fixed by the London and Edinburgh Colleges of Physicians at 0-838, whilst the Dublin College fixes it at 0.840.

In commerce the strength of mixtures of alcohol and water is stated at so many degrees, according to Sykes's hydrometer, above or below proof. This instrument will be explained under the head of Alcoholometry.

As will have been understood by the preceding remarks, the specific gravity or density of mixtures of alcohol and water rises with the diminution of the quantity of alcohol present ; or, in other words, with the amount of water. And since the strength of spirits is deter- mined by ascertaining their density, it becomes highly important to determine the precise ratio of this increase. This increase in density, with the amount of water, or diminution with the quantity of alcohol, is, however, not directly proportional, in consequence of the contraction of volume which mixtures of alcohol and water suffer.

It therefore became necessary to determine the density of mixtures of known composi- tion, prepared artificially. This has been done recently with great care by Mr. Drink- water ;* and the following table by him is recommended as oneof the most accurate :

Table of the Quantity of Alcohol, by weight, contained in Mixtures of Alcohol and Water of the following Specific Gravities: —

Specific	Alcohol, per cent, by weight.	Specific	Alcohol, per cent, by weight.	Specific	Alcohol, |	Specific	Alcohol,	Specific	Alcohol, per cent. by weight.
Gravity at 60° F.	Gravity at 00° F.	Gravity at 60° F.	pei ( cent, by weight.	Jravity t 60° F.	per ( cent, by weight.	Gravity t 60° F.
1-0000	o-oo	•9967	1-78	•9934	3-67	•9901	5-70	■9S69	7-85
	9999	0-05	•9966	1-83	•9933	3-73	■9900	5-77	•9868	7-92
	9998	o-n	•9965	1-89	•9932	8-78	9899	5-83	•9867	7-99
	999V	0-16	•9964	1-94	•9931	3-84	■9898	5-89	•9866	8-06
	9996	0-21	•9963	1-99	•9930	3-90	•9897	5-96	•9865	8-13
	9995	0-26	•9902	2-05	•9929	3-96	9896	6-02	•9S64	8-20
	9994	0-32	•9961	2-11	•9928	4-02	•9895	6-09	•9863	8-27
	9993	0-37	•9960	2-17	■9927	4-08	•9894	6-15	•9862	8-34
	9992	0-42	•9959	2-22	•9926	4-14	9893	6-22	•9861	8-41
	9991	0-47	•9958	2-28	•9925	4-20	9S92	6-29	9860	8-48
	9990	0-53	•9957	2-34	•9924	4-27	•9891 .	6-35	9859	8-55
	•9989	0-58	•9956	2-39	•9923	4-33	■9890	6-42	•9858	8-62
	■9988	0-64	•9955	2-45	•9922	4-39	•9889	6-49	•9857	8-70
	9987	0-69	•9954	2-51	•9921	4-45	9888	6-55	9856	8-77
	9986	0-74	•9953	2-57	•9920	4-51	9887	6-62	9855	8-84
	•9985	0-80	•9G52	2-62	•9919	4-57	98S6	6-69	•9854	8-91
	•9984	0-85	•9951	2-68	•9918	4-64	9885	6-75	•9853	8-98
	■9983	0-91	■9950	2-74	•9917	4-70	9SS4	6-82	9852	9-05
	•9982	0-96	•9949	2-79	•9916	4-76	9S83	6-89	■9851	9-12
	•9981	1-02	•9948	2-85	•9915	4-82	98S2	6-95	9850	9-20
	•9980	1-07	•9947	2-91	•9914	4-88	9881	7-02	9849	9-27
	•9979	1-12	•9946	2-97	•9913	4-94	98S0	7-09	9848	9-34
	9978	1-18	•9945	3-02	■9912	5-01	9879	7-16	9847	9-41
	9977	1-23	•9944	3-08	•9911	5-07	9878	7-23	9846	9-49
	9976	1-29	•9943	3-14	•9910	5-13	9877	7-30	9845	9-56
	9975	1-34	•9942	3-20	•9909	5-20	9876	7-37	9844	9-63
	9974	1-40	•9941	3-26	•9908	5-26	9875	7-43	9843	9-70
	9973	1-45	•9940	3-32	•9907	5-32	9874	7-50	9842	9-78
	9972	1-51	•9939	3-37	•9906	5-39	9873	7-57	9841	9-S5
	9971	1-56	•9938	3-43	•9905	5-45	9872	7-64	9840	9-92
	9970	1-61	•9937	3-49	•9904	5-51	9871	7-71	9S39	9-99
	9969	1-67	•9936	3-55	•9903	5-58	9870	7-78 ■	9838	10-07
•9968	1-73	•9935	3-61	•9902	5-64				1

* Memoirs of tlio Chemical Society, vol. iii. p. 434.

ALCOHOL.

Q"l

The preceding table, though very accurate so far as it goes, is not sufficiently extensive for practical purposes, only going, in fact, from 6 to 10 per cent, of alcohol ; the table of Trailed (below) extends to 50 per cent, of absolute alcohol.

Moreover, Drinkwater's table has the (practical) disadvantage (though scientifically more correct and useful) of stating the percentage by weight ; whereas, in Tralle's table, it is givan by volume. And since liquors are vended by measure, and not by weight, the centesimal amount by volume is usually preferred. But as the bulk of liquids generally, and par- ticularly that of alcohol, is increased by heat, it is necessary that the statement of the den- sity in a certain volume should have reference to some normal temperature. In the construction of Tralle's table the temperature of the liquids was 60° F. ; and, of course, in using it, it is necessary that the density should be observed at that temperature.

In order to convert the statement of the composition by volume into the content by weight, it is only necessary to multiply the percentage of alcohol by volume by the specific gravity of absolute alcohol, and then divide by the specific gravity of the liquid.

Tralle's Table of the Composition, by volume, of Mixtures of Alcohol and Water of

different Densities.

Per- centage of Alcohol by volume.	Specific Gravity at 60° F.	Differ- ence of the spe- cific gra- vities.	Per- centage of Alcohol by volume.	Specific Gravity at 60° F.	Differ- ence of the spe- cific gra- vities.	Per- centage of Alcohol by volume.	Specific Gravity at 60° F.	Differ- ence of the spe- cific gra- vities.
0	0-9991		34	0-9596	13	68	0-8941	24
1	0-9976	15	35	. 0-9583	13	69	0-8917	24
2	0-9961	15	36	0=9570	13	70	' 0-8892	25
3	0-9947	14	37	09556	14	71	0-8867	25
4	0-9933	14	38	0-9541	15	72	0-8842	25
5	09919	14	39	09526	15	73	0-8817	25
6	0-9906	13	40	0-9510	16	74	0-8791	26
7	0-9893	13	41	0-9494	16	75	0-8765	26
8	0-9881	12	42	0-9478	16	76	0-8739	26
9	0-9869	12	43	0-9461	17	77	0-8712	27
10	0-9857	12	44	0-9444	17	78	0-8685	27
11	0-9845	12	45	0-9427	17	79	0-8658	27
12	0-9834	11	46	0-9409	18	80	0-8631	27
13	0-9823	11	47	0-9391	18	81	0-8603	28
14	0-9812	11	48	0-9373	18	82	0-8575	28
15	0-9802	10	49	0-9354	19	83	0-8547	28
16	0-9791	11	50	0-9335	19	84	0-8518	29
17	0-9781	10	51	0-9315	20	85	0-8488	30
18	0-9771	10	52	0-9295	20	86	0-8458	30
19	0-9761	10	53	0-9275	20	87	0-8428	30
20	0-9751	10	54	0-9254	21	88	0-8397	31
21	0-9741	10	55	0-9234	20	89	0-8365	32
22	0-9731	10	56	0-9213	21	90	0-8332	33
23	0-9720	11	57	0-9192	21	91	0-8299	33
24	0-9710	10	58	0-9170	22	92	0-8265	34
25	0-9700	10	59	0-9148	22	93	0-8230	35
26	0-9689	11	60	0-9126	22	94	0-8194	36
27	0-9679	10	61	0-9104	22	95	0-8157	37
28	0-9668	11	62	0-9082	22	96	0-8118	39
29	0-9657	11	63	0-9059	23	97	0-8077	41
30	0-9646	11	64	0-9036	23	98	0-8034	43
31	0-9634	12	65	0-9013	23	99	0-7988	46
32	0-9622	12	66	0-8989	24	100	0-7939	49
33	0-9609	13	67	0-8965	24

In order, however, to employ this table for ascertaining the strength of mixtures of alcohol and water of different densities (which is the practical use of such tables), it is absolutely necessary that the determination of the density should bo performed at an inva- riable temperature, — viz. 60° F. The methods of determining the density will be hereafter described ; but it is obvious that practically the experiment cannot be conveniently made at any fixed temperature, but must be performed at that of the atmosphere.

32

ALCOHOL.

The boiling point of mixtures of alcohol and water likewise differs with the stength of such mixtures.

According to Gay-Lussac, absolute alcohol boils at 78-4° C. (173° F.) under a pressure of 760 millimetres (the millimetre being 0'03937 English inches). When mixed with water, of course its boiling point rises in proportion to the quantity of water present, as is the case in general with mixtures of two fluids of greater and less volatility. A mixture of alcohol and water, however, presents this anomaly, according to Soemmering : when the mixture contains less than six per cent, of alcohol, those portions which first pass off are saturated with water, and the alcoholic solution in the retort becomes richer, till absolute alcohol passes over ; but when the mixture contains more than six per cent, of water, the boiling point rises, and the quantity of alcohol in the distillate steadily diminishes as the distillation proceeds.

According to Groning's researches, the following temperatures of the alcoholic vapors correspond to the accompanying contents of alcohol in percentage of volume which are disengaged in the boiling of the spirituous liquid.

	Alcoholic con-	Alcoholic con-		Alcoholic con-	Alcoholic con-
Temperature.	tent of the	tent of the	Temperature.	tent of the	tent of the
	vapor.	boiling liquid.		vapor.	boiling liquid.
Fahr. 170-0	93	92	Fahr. 189-8	71	20
171-8	92	90	192-0	68	18
172	91	85	164	66	15
172-8	90£	80	196-4	61	12
174	90	70	198-6	55	10
174-6	89	70	201	50	7
176	87	65	203	42	5
178-3	85	50	205-4	36	3
180-8	82	40	207-7	28	2
183	80	35	210	13	1
185	78	30	212	0	0
187-4	76	25

Groning undertook this investigation in order to employ the thermometer as an alcoho- lometer in the distillation of spirits ; for which purpose he thrust the bulb of the thermom- eter through a cork inserted into a tube fixed in the capital of the still. The state of the barometer ought also to be considered in making comparative experiments of this kind. Since, by this method, the alcoholic content may be compared with the temperature of the vapor that passes over at any time, so, also, the contents of the whole distillation may be found approximately ; and the method serves as a convenient means of making continual observations on the progress of the distillation.

Density of the Vapor. — One volume of alcohol yields 488-3 volumes of vapor at 212° F. The specific gravity of the vapor, taking air as unity, was found by Gay-Lussac to be 1-6133. [Its vapor-density, referred to hydrogen, as unity, is 13-3605 ?]

Spirituous vapor passed through an ignited tube of glass or porcelain is converted into carbonic oxide, water, hydrogen, carburetted hydrogen, defiant gas, naphthaline, empyreu- matic oil, and carbon; according to the degree of heat and nature of the 'tube, these products vary. Anhydrous alcohol is a non-conductor of electricity, but is decomposed by a powerful voltaic battery. Alcohol burns in the air with a blue flame into carbonic acid and water ; the water being heavier than the spirit, because 46 parts of alcohol contain 6 of hydrogen, which form 54 of water. In oxygen the combustion is accompanied with great heat, and this flame, directed through a small tube, powerfully ignites bodies exposed to it.

Platinum in a finely divided state has the property of determining the combination of alcohol with the oxygen of the air in a remarkable manner. A ball of spongy platinum, placed slightly above the wick of a lamp, fed by spirit, and communicating with the wick by a platinum wire, when once heated, keeps at a red heat, gradually burning the spirit. This has been applied in the construction of the so-called " philosophical pastilles ; " eau-de- cologne or\other perfumed spirit being thus made to diffuse itself in a room.

Mr. Gilfhas also practically applied this in the construction of an alcohol lamp without flame.

A coil of platinum wire, of about the one-hundreth part of an inch in thickness, is coiled partly round the cotton wick of a spirit lamp, and partly above it, and the lamp lighted to heat the wire to redness ; on the flame being extinguished, the alcohol vapor keeps the wire red hot for any length of time, so as to be in constant readiness to ignite a match, for example. This lamp affords sufficient light to show the hour by a watch in the night, with a very small consumption of spirit.

ALCOHOL. 33

This property of condensing oxygen, and thus causing the union of it with combustible bodies, is not confined to platinum, but is possessed, though in a less degree, by other porous bodies. If we moisten sand in a capsule with absolute alcohol, and cover it with previously heated nickel powder, protoxide of nickle, cobalt powder, protoxide of cobalt, protoxide of uranium, or oxide of tin (these six bodies being procured by ignition of their oxalates in a crucible), or finely powdered peroxide of manganese, combustion takes place, and continues so long as the spirituous vapor lasts.

Solvent Power. — One of the properties of alcohol most valuable in the arts is its solvent power.

It dissolves gases to a very considerable extent, which gases, if they do not enter into com- binations with the alcohol, or act chemically upon it, are expelled again on boiling the alcohol.

Several salts, especially the deliquescent, are dissolved by it, and some of them give a color to its flame ; thus the solutions of the salts of strontia in alcohol burn with a crimson fame, those of copper and borax with a green one, lime a reddish, and baryta with a yellow flame.

This solvent power is, however, most remarkable in its action upon resins, ethers, essen- tial oils, fatty bodies, alkaloids, as well as many organic acids. In a similar way it dissolves iodine, bromine, and in small quantities sulphur and phosphorus. In general it may be said to be an excellent solvent for most hydrogenized organic substances.

In consequence of this property it is most extensively used in the chemical arts ; e. g. for the solution of gum-resins, &c, in the manufacture of varnishes ; in pharmacy, for the separating of the active principles of plants, in the preparation of tinctures. It is also em- ployed in the formation of chloroform, ether, spirits of nitre, &c.

Methylated Spirit. — It was, therefore, for a long time a great desideratum for the manufacturer to obtain spirit free from duty. The Government, feeling the necessity for this, have sanctioned the sale of spirit which has been flavored with methyl-alcohol, so as to render it unpalatable, free of duty under the name of " methylated spirit.'''' This methylated spirit can now be obtained, in large quantities only, and by giving suitable security to the Board of Inland Revenue of its employment for manufacturing purposes only, and must prove of great value to those manufacturers who are large consumers.

Professors Graham, Hoffmann, and Redwood, in their " Report on the Supply of Spirit of Wine, free of duty, for use in the Arts and Manufactures," addressed to the Chairman of the Board of Inland Revenue, came to the following conclusions : —

" From the results of this inquiry, it has appeared that means exist by which spirit of wine, produced in the usual way, may be rendered unfit for human consumption, as a beverage, without materially impairing it for the greater number of the more valuable pur- poses in the arts to which spirit is usually applied. To spirit of wine, of not less strength than corresponds to density 0'830, it is proposed to make an addition of 10 per cent, of purified wood naphtha (ivood or methylic spirit), and to issue this mixed spirit for consump- tion, duty free, under the name of Methylated Spirit. It has been shown that methylated spirit resists any process for its purification ; the removal of the substance added to the spirit of wine being not only difficult, but, to all appearance, impossible ; and further, that no danger is to be apprehended of the methylated spirit being ever compounded so as to make it palatable. . . It may be found safe to reduce eventually the proportion of the mixing ingredient to 5 per cent., or even a smaller proportion, although it has been recommended to begin with the larger proportion of 10 per cent."

And further, the authors justly remark : — " The command of alcohol at a low price is sure to suggest a multitude of improved processes, and of novel applications, which can scarcely be anticipated at the present moment. It will be felt far beyond the limited range of the trades now more immediately concerned in the consumption of spirits ; like the repeal of the duty on salt, it will at once most vitally affect the chemical arts, and cannot fail, ultimately, to exert a beneficial influence upon many branches of industry."

And in additional observations, added subsequently to their original report, the chem- ists above named recommend the following restriction upon the sale of the methylated spirit : — " That the methylated spirit should be issued by agents duly authorized by the Board of Inland Revenue, to none but manufacturers, who should themselves consume it ; and that application should always be made for it according to a recognized form, in which, besides the quantity wanted, the applicant should state the use to which it is to be applied, and undertake that it should be applied for that purpose only. The manufacturer might be permitted to retail varnishes and other products containing the methylated spirit, but not the methylated spirit itself, in an unaltered state." They recommend that the methylated spirit should not be made with the ordinary crude, very impure wood naphtha, since this could not be advantageously used as a solvent for resins by hatters and varnish-makers, as the less volatile parts of the naphtha would be retained by the resins after the spirit had evaporated, and the quality of the resin would be thus impaired. If, however, the methy- lated spirit be originally prepared with the crude wood naphtha, it may be purified by a simple distillation from 10 per cent, of potash. Vor,. TTT.— ".

Si ALCOHOLOMETEY.

_ It appears that the boon thus afforded to the manufacturing community of obtaining spirit dutyfree has been acknowledged and appreciated ; and now for most purposes, where the small quantity of wood-spirit does not interfere, the methylated spirit is generally used. It appears that even ether and chloroform, which one would expect to derive an un- pleasant flavor from the wood-spirit, are now made of a quality quite unobjectionable from the methylated spirit ; but care should be taken, especially in the preparation of medicinal compounds, not to extend the employment of the methylated spirit beyond its justifiable limits, lest so useful an article should get into disrepute!* Methylated spirit can be pro- cured also in small quantities from the wholesale dealers, containing in solution 1 oz. to the gallon of shellac, under the name of " finish."

Alcoholatcs. — Graham has shown that alcohol forms crystallizable compounds wit!: several salts. These bodies, which he calls " Alcoholates," are in general rather unstable combinations, and almost always decomposed by water. Among the best known are the following : —

Alcoholate of chloride of calcium - - - 2 C4H602, Ca CI

" of zinc - - - C4H°02, Zn CI

" bichloride of tin ... C4Hc02, Tn CI

" nitrate of magnesia - - - 3 C4H°02, Mg 0, K06

ALCOHOLOMETRY, or ALCOOMETRY. Determination of the Strength of Mixtures of Alcohol and Water. Since the commercial value of the alcoholic liquors, commonly called "spirits," is determined by the amount of pure or absolute alcohol present in them, it is evident that a ready and accurate means of determining this point is of the highest importance to all persons engaged in trade in such articles.

If the mixture contain nothing but alcohol and water, it is only necessary to determine the density or specific gravity of such a mixture ; if, however, it contain saccharine matters, coloring principles, &c, as is the case with wine, beer, &c, other processes become neces- sary, which will be fully discussed hereafter.

The determination of the specific gravity of spirit, as of most other liquids, may be effected, with perhaps greater accuracy than by any other process, by means of a stoppered specific gravity bottle. If the bottle be of such a size as exactly to hold 1,000 grains of distilled water at 60° F., it is only necessary to weigh it full of the spirit at the same tem- perature, when (the weight of the bottle being known) the specific gravity is obtained by a very simple calculation. See Specific Gravity.

This process, though very accurate, is somewhat troublesome, especially to persons unaccustomed to accurate chemical experiments, and it involves the possession of a delicate balance. The necessity for this is however obviated by the employment of one of the many modifications of the common hydrometer. This is a floating instrument, the use of which depends upon the principle, that a solid body immersed into a fluid is buoyed upwards with a force equal to the weight of the fluid which it displaces, i. e. to its own bulk of the fluid ; consequently, the denser the spirituous mixture, or the less alcohol it contains, the higher will the instrument stand in the liquid ; and the less dense, or the more spirit it contains, the lower will the apparatus sink into it.

There are two classes of hydrometers : 1st. Those which are always immersed in the fluid to the same depth, and to which weights are added to adjust the instrument to the density of any particular fluid. Of this kind are Fahrenheit's, Nicholson's, and Guyton de Morveau's hydrometers.

2d. Those which are always used with the same weight, but which sink into the liquids to be tried, to different depths, according to the density of the fluid. Of this class are most of the common glass hydrometers, such as Beaume's, Curteis's, Gay-Lussac's, Twaddle's, &c.

Sykes's and Dicas's combine both principles. See Hydrometers.

Sykes's hydrometer, or alcoholometer, is the one employed by the Board of Excise, and therefore the one most extensively used in this country.

This instrument does not immediately indicate the density or the percentage of absolute alcohol, but the degree above or below proof — the meaning of which has been before detailed ; (p. 30.)

It consists of a spherical ball or float, a, with an upper and lower stem of brass, b and c. The upper stem is graduated into ten principal divisions, which are each subdivided into five parts. The lower stem, c, is made conical, and has a loaded bulb at its extremity. There are nine movable weights, numbered respectively by tens from 10 to 90. Each of these circular weights has a slit in it, so that it can be placed on the conical stem, c. The instrument is adjusted so that it floats with the surface of the fluid coincident with zero on the scale in a spirit of specific gravity -825 at 60° F., this being accounted by the Excise as " standard alcohol.'1'' In weaker spirit, which has therefore a greater density, the hydrom-

* Some difference of opinion appenrs to exist whether Chloroform can be obtained pure from me- thylated spirit.

ALCOHOLOMETRY.

35

eter will not sink so low ; and if the density be much greater, it will be necessary to add one of the weights to cause the entire immersion of the bulb of the instrument. Each weight represents so many principal divisions of the stem as its number indicates ; thus, the heaviest weight, marked 90, is equivalent to 90 divisions of the stem, and the instrument, with the weight added, floats at 0 in distilled water. As each principal division on the stem is divided into five subdivisions, the instrument has a range of 500 degrees be- tween the standard alcohol (specific gravity -825) and water. There is a line on one of the side faces of the stem, 6, near division 1 of the draw- ing, at which line the instrument with the weight 60 attached to it, floats in spirits exactly of the strength of proof, at a temperature of 51° F.

In using this instrument, it is immersed in the spirit, and pressed down by the hand until the whole of the graduated portion of the upper stem is" wet. The force of the hand required to sink it will be a guide to the selection of the proper weight. Having taken one of the circular weights necessary for the purpose, it is slipped on to the lower conical stem.

The instrument is again immersed, and pressed down as before to 0, and then allowed to rise and settle at any point. The eye is then brought to the level of the surface of the spirit, and the part of the stem cut by the surface as seen from below, is marked. The number thus indicated by the stem is added to the number of the weight, and the sum of these, together with the temperature of the spirit, observed at the same time by means of a thermometer, enables the operator, by reference to a table which is sold to accompany the instrument, to find the strength of the spirit tested.

These tables are far too voluminous to be quoted here ; and this is unnecessary, since the instrument is never sold without them.

A modification of Sykes's hydrometer has been recently adopted for testing alcoholic liquors, which is perhaps more convenient, as the neces- sity for the loading weights is done away with, the stem being sufficiently long not to require them. It is constructed of glass, and is in the shape of a common hydrometer, the stem being divided into degrees ; it carries a small spirit thermometer in the bulb, to which a scale is fixed, ranging from 30° to 82° F. (0 to 12° C.) There are tables supplied with the hydrometer, which are headed by the degrees and half degrees of the thermometric scale ; and the corresponding content of spirit, over or under proof at the respective degrees of the table, is placed opposite each degree of the hydrometer. See Spirits, vol. ii.

In France, Gay-Lussac's alcoolometre is usually employed. It is a common glass hydrometer, with the scale on the stem divided into 100 parts or degrees. The lowest division, marked 0, denotes the specific gravity of pure water; and 100, that of absolute alcohol, both at 15° C. (59° F.) The intermediate degrees, of course, show the percentage of absolute alcohol by volume at 15° C. ; and the instrument is accompanied by the tables already given for ascertaining the percentage at any other temperature.

Alcoholometry of Liquids containing besides Alcohol, Saccharine Matters, Coloring Principles, Src, such as Wines, Beer, Liqueurs, Sfc.

In order to determine the proportion of absolute alcohol contained in wines or other mixtures of alcohol and water with saccharine and other non-volatile substances, the most accurate method consists in submitting a known volume of the liquid to distillation, (in a glass retort, for instance ;) then, by determining the specific gravity of the distilled product, to ascertain the percentage of alcohol in this distillate, which may be regarded as essentially a mixture of pure alcohol and water. The distillation is carried on until the last portions have the gravity of distilled water ; by then ascertaining the total volume of the distillate, and with the knowledge of its percentage of alcohol and the volume of the original liquor used, the method of calculating the quantity of alcohol present in the wine, or other liquor, is sufficiently obvious.

In carrying out these distillations, care must be taken to prevent the evaporation of the spirit from the distillate, by keeping the condenser cool. And Professor Mulder recom- mends the use of a refrigerator, consisting of a glass tube fixed in the centre of a jar, so that it may be kept filled with cold water. The tube must be bent at a right angle, and terminate in a cylindrical graduated measure-glass, shaped like a bottle.*

It is well to continue the distillation until about two-thirds of the liquid has passed over.

This process, though the most accurate for the estimation of the strength of alcoholic

* The Chemistry of "Wine, by G. J. Mulder, edited by II. Beuce Jones, M. D.

36

ALOOHOLOMETEY.

liquors, is still liable to error. The volatile aeids and ethers pas3 over with the alcohol into the distillate, and, to a slight extent, affect the specific gravity. This error may be, to a great extent, overcome by mixing a little chalk with the wine, or other liquor, previous to distillation.

By this method Professor Brande made, some years ago, determinations of the strength of the following wines, and other liquors * ; —

Proportion of Spirit per Cent, by Measure,

Lissa -	average	25-41	Orange	.	average	11-26
Raisin -	u	25-12	Elder	.		u	S-79
Marsala	(C	25-09
Port (of 7 samples)	C(	22-96	Cider	average	5-21 to i
Madeira	"	22-27	Perry		u		7-26
Sherry (of 4 samples)	«	19-17	Mead		u		7-32
Teneriffe	-	19-79	Ale, Burton 1				( 8-88
Lisbon -	-	18-94	Ale, Edinburgh v	average	6-87	1 6'20
Malaga -	-	18-94	Ale, Dorchester )				f 5-55
Bucellas	-	18-49	Brown Stout	.	-		6-80
Cape Madeira	average	20-51	London Porter -	.	average	4-20
Roussillon	(i	19.00	London Small Beer	.	.	"	1-28-
Claret -	tt	15-10
Sauterne	"	14-22	Brandy	.	.	it	53-39
Burgundv	K	14-57	Rum	.	.	u-	53-68
Hock -	U	1208	Gin	-	.	«	57-60
Tent -	(C	13-30	Scotch Whiskey	-	-	u	54-32
Champagne -	u	12-61	Irish Whiskey -	-	-	"	53-90
Gooseberry -	cc	11-84
The following results were obtained by	the writer more rece	ntly by	this process,
(1854.)
	Percentage of Alcohol by Volume.
Port (1834) -	-	22-46	Port (best)	.	-	.	20-2
Sherry (Montilla)	-	19-95	Marcobrunner	-	-	-	8-3
Madeira	-	22-40	Champagne (1st)	-	-	-	12-12
Claret (Haut Brion)	-	10-0	Champagne (2d)	-	-	-	10-85
Chambertin	-	11-7	Home Ale	.	.	.	6-4
Sherry (low quality)	-	20-7	Export Ale	-	.	-	6-4
Sherry (brown)	-	23-1	Strong Ale	.	-	-	9-0
Amontillado	-	20-5	Stout	.	.	.	5-7
Mansanilla	-	14.4	Porter -	-	-	-	4-18

M. l'Abbe Brossard-Vidal, of Toulonf, has proposed to estimate the strength of alcoholic liquors by determining their boiling point. Since water boils at 100° C. (212° F.), and absolute alcohol at 78-4° (173° F.), it is evident that a mixture of water and alcohol will have a higher boiling point the larger the quantity of water present in it. This method is even applicable to mixtures containing other bodies in solution besides spirit and water, since it has been shown that sugar and salts, when present, (in moderate quantities,) have only a very trifling effect in raising the boiling point ; and the process has the great advan- tage of facility and rapidity of execution, though, of course, not comparable to the method by distillation, for accuracy.

Mr. Field's patent (1847) alcoholometer is likewise founded upon the same principle. The instrument was subsequently improved by Dr. Ure.

The apparatus consists simply of a spirit-lamp placed under a little boiler containing the alcoholic liquor, into which fits a thermometer of very fine bore.

When the liquor is stronger than proof-spirit, the variation in the boiling point is so small that an accurate result cannot possibly be obtained ; and, in fact, spirit approaching this strength should be diluted with an equal volume of water before submitting it to ebulli- tion, and then the result doubled.

Another source of error is the elevation of the boiling point, when the liquor is kept heated for any length of time ; it is, however, nearly obviated by the addition of common salt to the solution in the boiler of the apparatus, in the proportion of 35 or 40 grains. In order to correct the difference arising from higher or lower pressure of the atmosphere, the scale on which the thermometric and other divisions are marked is made movable up and

Brando's Manual of Chemistry ; also Philosophical Trans., 1S11. t Comptes Eendus, xsvii. 3T4.

ALCOHOLOMETKY.

37

down the thermometer tube ; and every time, before commencing a set of experiments, a preliminary experiment is made of boiling some pure distilled water in the apparatus, and the zero point on the scale (which indicates the boiling point of water) is adjusted at the level of the surface of the mercury.

But even when performed with the utmost care, this process is still liable to very considerable errors, for it is extremely difficult to observe the boiling point to within a decree ; and after all, the fixed ingredients present undoubtedly do seriously raise the boil- in^ point of the mixture — in fact, to the extent of from half to a whole degree, according to the amount present..

Silbermann's Method. — H. Silbermann* has proposed another method of estimating the strength of alcoholic liquors, based upon their expansion by heat. It is well known that, between zero and 100° C. (212° F.), the dilatation of alcohol is triple that of water, and this difference of expansion is even greater between 25° C. 8

(77° F.) and 50° C. (122° F.) ; it is evident, therefore, that the expansion between these two temperatures becomes a measure of the amount of al- cohol present in any mixture. The presence of salts and organic sub- stances, such as sugar, coloring, and extractive matters, in solution or suspension in the liquid, is said not materially to affect the accuracy of the result ; and M. Silbermann has devised an apparatus for applying this principle, in a ready and expeditious manner, to the estimation of the strength of alcoholic liquors. The instrument may be obtained of the philosophical instrument-makers of London and of Liverpool.

It consists of a brass plate, on which are fixed — 1st, An ordinary mer- curial thermometer graduated from 22° to 50° 0. (11° to 122° F.), these being the working temperatures of the dilat.atomeicr ; and 2dly, the dilatatometer itself, which consists of a glass pipette, open at both ends, and of the shape shown in the figure. A valve of cork or india-rubber closes the tapering end, a, which valve is attached to a rod, b b, fastened to the supporting plate, and connected with a spring, n, by which the lower orifice of the pipette can be opened or closed at will. The pipette is filled, exactly up to the zero point, with the mixture to be examined — this being accomplished by the aid of a piston working tightly in the long and wide limb of the pipette ; the action of which serves also another valuable purpose, viz., that of drawing any bubbles of air out of the liquid. By now observing the dilatation of the column of liquid when the temperature of the whole apparatus is raised, by immersion in a water-bath, from 25° to 50°, the coefficient of expansion of the liquid is obtained, and hence the proportion of alcohol — the instrument being, in fact, so graduated, by experiments previously made upon mixtures of known composition, as to give at once the percentage of alcohol.

Another alcoholometer, which, like the former, is more remarkable for the great facility and expedition with which approximative results can be obtained than for a high degree of accuracy, was invented by M. Geisler, of Bonn, and depends upon the measurement of the tension of the vapor of the liquid, as indicated by the height to which it raises a column of mercury.

Geisler's Alcoholometer. — It consists of a closed vessel in which the alco- 9 holic mixture is raised to the boiling point, and the tension of the vapor ob- served by the depression of a column of mercury in one limb of a tube, the indication being rendered more manifest by the elevation of the other end of the column.

The wine or other liquor of which it is desired to ascertain the strength, is put into the little flask, f, which, when completely filled, is screwed on to the glass which contains mercury, and is closed by a stopcock at s. The entire apparatus, which at present is an inverted position, is now stood erect, the flask and lower extremity of the tube being immersed in a water-bath. The vinous liquid is thus heated to a boiling point, and its vapor forces the mercury up into the long limb of the tube. The instrument having been graduated, once for all, by actual ex- periment, the percentage of alcohol is read off at once on the stem by the height to which the mercurial column rises. f

To show how nearly the results obtained by this instrument agree with those obtained by the distillation process, comparative experiments were made on the s same wines by Dr. Bence Jones, f

* Comptes Rendus, xxvii. 418.

t On the Acidity, Sweetness, and Strength of different Wines, by II. Bence Jones, M. D., F. It. S., Proceedings of the Royal Institution, February, 1854.

38 ALCOHOLOMETEY.

By Distillation (Mr. Witt) By Alcoholometer per cent, by measure, per cent, by measure.

Port, 1834, ..... 22-46 . . i H'%

(20-1 Sherry, Montilla, .... 19-95 . . -j 20-6

(20-6 Madeira, ..... 22-40 . . 4 23-a

Haut Brion claret, .... 10-0 . . \]].\

Chambertin, . . . . 11-7 . .

Low-quality sherry, .... 20-7

Brown sherry, ..... 23-l Amontillado, . . . . 20-5- .

Mansanilla, ..... 14-4

( iO'4

Port, best, 20-2 . . j *JJ

Marcobrunner, . . . . 8-3 . . ■] 1.

Home ale, . . . . . 6-4 . . j £°

Export ale, . . . . . W . . j ^

Strong ale, 2-0 .. j }JJ

Tabariffs Method. — There is another method of determining the alcoholic contents of mixtures, which especially recommends itself on account of its simplicity. The specific gravity of the liquor is first determined, half its volume is next evaporated in the open air, sufficient water is then added to the remainder to restore its original volume, and the spe- cific gravity again ascertained. By deducting the specific gravity before the expulsion of the alcohol from that obtained afterwards, the difference gives a specific gravity indicating the percentage of alcohol, which may be found by referring to Gay-Lussac's or one of the other Tables. Tabarie has constructed a peculiar instrument for determining these specific gravities, which he calls an cenometer ; but they may be performed either by a specific- gravity bottle or by a hydrometer in the usual way.

Of course this method cannot be absolutely accurate ; nevertheless, Prof. Mulder's ex- perience with it has led him to prefer it to any of the methods before described, especially where a large number of samples have to be examined. He states that the results are almost as accurate as those obtained by distillation. The evaporation of the solution may be accelerated by conducting hot steam through it.

Adulterations. — Absolute alcohol should be entirely free from water. This may be recognized by digesting the spirit with pure anhydrous sulphate of copper. If the spirit contain any water, the white salt becomes tinged blue, from the formation of the blue hydrated sulphate of copper.

Rectified spirit, proof spirit, and the other mixtures of pure alcohol and water, should be colorless, free from odor and taste. If containing methylic or amylie alcohols, they are immediately recognized by one or other of these simple tests.

Dr. Ure states, that if wood spirit be contained in alcohol, it may be detected to the greatest minuteness by the test of caustic potash, a little of which, in powder, causing wood spirit to become speedily yellow and brown, while it gives no tint to alcohol. Thus 1 per cent, of wood spirit may be discovered in any sample of spirits of wine.

The admixture with a larger proportion than the due amount of water is of course de- termined by estimating the percentage of absolute alcohol by one or other of the several methods just described in detail.

The adulterations and sophistications to which the various spirits known as rum, brandy whiskey, gin, &c, are subjected, will be best described under these respective heads, since these liquors are themselves mixtures of alcohol and water with sugar, coloring matters, flavoring ethers, &c.

ALDEHYDE. By this word is understood the fluid obtained from alcohol by the removal of two equivalents of hydrogen. Thus, alcohol being represented by the formula D4 H6 0", aldehyde becomes C4 H4 0\

ALDER. 39

Preparation. — Aldehyde is prepared by various processes of oxidation. Liebig has published several methods, of which the following is perhaps the best : Three parts of peroxide of manganese, three of sulphuric acid, two of water, and two of alcohol of 80 per cent., are well mixed and carefully distilled in a spacious retort. The extreme volatility of aldehyde renders good condensation absolutely necessary. The contents of the retort are to be "distilled over a gentle and manageable fire until frothing commences, or the distillate becomes acid. This generally takes place when about one-third has passed over. The fluid in the receiver is to have about its own weight of chloride of calcium added, and, after slight digestion, is to be carefully distilled on the water-bath. The distillate is again to be treated in the same way. By these processes a fluid will be obtained entirely free from water, but containing several impurities. To obtain the aldehyde in a state of purity, it is necessary, in the first place, to obtain aldehyde-ammonia ; this may be accomplished in the follewing manner : — The last distillate is to be mixed in a flask with twice its volume of ether, and, the flask being placed in a vessel surrounded by a freezing mixture, dry ammo- niacal gas is passed in until the fluid is saturated. In a short time crystals of the com- pounds sought separate in considerable quantity. The aldehyde-ammonia, being collected on a filter, or in the neck of a funnel, is to be washed with ether, and dried by pressure between folds of filtering paper, followed by exposure to the air. It now becomes neces- sary to obtain the pure aldehyde from the compound with ammonia. For this purpose two parts are to be dissolved in an equal quantity of water, and three parts of sulphuric acid, mixed with four of water, are to be added. The whole is to be distilled on the water-bath, the temperature, at first, being very low, and the operation being s opped as soon as the water boils. The distillate is to be placed in a retort connected with a good condensing apparatus, and, as soon as all the joints are known to be tight, chloride of calcium, in frag- ments, is to be added. The heat arising from the hydration of the chloride causes the dis- tillation to commence, but it is carried on by a water-bath. The distillate, after one more rectification over chloride of calcium, at a temperature not exceeding 80° F., will consist of pure aldehyde. Aldehyde is a colorless, very volatile, and mobile fluid, having the den- sity 0'800 at 32°. It boils, under ordinary atmospheric pressure, at '10" F. Its vapor density is 1'532. Its formula corresponds to four volumes of vapor ; we consequently obtain the theoretical vapor density by multiplying its atomic weight = 44 by half the density of hydrogen, or .0346. The number thus found is 1-5224, corresponding as nearly as could be desired to the experimental result.

Aldehyde is produced in a great number of processes, particularly during the destructive distillation of various organic matters, and in processes of oxidation. From alcohol, alde- hyde may be procured by oxidation with platinum black, nitric acid, chromic acid, chlorine (in presence of water), or, as we have seen, a mixture of peroxide of manganese and sul- phuric acid. Certain oils, by destructive distillation, yield it. Wood vinegar in the crude state contains aldehyde as well as wood spirit. Lactic acid, when in a combination with weak bases, yields it on destructive distillation. Various animal and vegetable products afford aldehyde by distillation with oxidizing agents, such as sulphuric acid and peroxide of manganese, or bichromate of potash.

The word aldehyde, like that of alcohol, is gradually becoming used in a much more extended sense than it was formerly. By the term is now understood any organic sub- stance which, by assimilating two equivalents of hydrogen, yields a substance having the properties of an alcohol, or, by taking up two equivalents of oxygen, yields an acid. It is this latter property which has induced certain chemists to say that there is the same relation between an aldehyde and its acid as between inorganic acids ending in ous and ic. Several very interesting and important substances are now known to belong to the class of alde- hydes. The essential oils are, in several instances, composed principally of bodies having the properties of aldehydes. Among the most prominent may be mentioned the oils of bitter almonds, cumin, cinnamon, rue, &c. An exceedingly important character of the aldehydes is their strong tendency to combine with the bisulphites of ammonia, potash, and soda. By availing ourselves of this property, it becomes easy to separate bodies of this class from complex mixtures, and, consequently, enable a proximate analysis to be made. Now that the character of the aldehydes is becoming better understood, the chances of arti- ficially producing the essential oils above alluded to in the commercial scale become greatly increased. Several have already been formed, and, although in very small quantities, the success has been sufficient to warrant sanguine hopes of success. A substitute for one of them has been for some years known under the very incorrect name of artificial oil of bitter almonds. See Nitrobenzole. — C. G. W.

ALDER. (Aune, Fr. ; Eric, Germ. ; Alnux glutinosa, Lin.) A tree, different species of which are indigenous to Europe, Asia, and America. The common alder seldom grows to a height of more than 40 feet. The wood is stated to be very durable under water. The piles at Venice, and those of Old London Bridge, are stated to have been of aider ; and it is much used for pipes, pumps, and sluices. The charcoal of this wood is used for gunpowder.

40

ALEMBIC.

10

ALEMBIC, a still {which see). The term is, however, applied to a still of peculiar con- struction, in which the head, or capital, is a separate piece, fitted and ground to the neck of the boiler, or cucurbit, or otherwise carefully united with a lute. The alembic has this advantage over the common retort, that the residue of distilla- tion may be easily cleared out of the body. It is likewise capable, when skilfully managed, of distilling a much larger quantity of liquor in a given time than a retort of equal ca] - city. In France the term alembic, or rather alambic. is listi. to designate a glass still.

ALGAROTH, POWDER OF. Powder of Algarotti,— English Powder. This salt was discovered by Algarotti, a physician of Verona. Chloride of antimony is formed by boiling black sulphide of antimony with hydrochloric acid : on pouring the solution into water, a white flocky precipitate falls, which is an oxichloride of antimony. If the water be hot, the precipitate is distinctly crystalline ; this is the powder of algaroth. This oxichloride is used to furnish oxide of antimony in the preparation of tartar emetic.

ALGiE. (Varech, Fr. ; Seegras, or Alge, Germ.) A tribe of subaqueous plants, in- cluding the seaweeds (focus) and the lavers {ulva) growing in salt water, and the fresh water confervas. We have only to deal with those seaweeds which are of any commercial value. These belong to the great division of the jointless algw, of which 160 species are known as natives of the British Isles. In the manufacture of Kelp, (see Kelp,) all the varie- ties of this division may be used. The edible sorts, such as the birds' nests of the Eastern Archipelago, those which we consume in this country, as layers, carrageen, or Irish moss, &c, belong to the same group, as do also those which the agriculturalists employ for manure. Dr. Pereira gives the following list of esculent seaweeds : —

Phodomenia palmata (or Dulse). Phodomenia ciliata. Lami.naria saccharina.

Iridcea edulis. Alaria escidenta. Ulva latissima.

Phodomenia palmata passes under a variety of names, dulse, dylish, or dellish, and amongst the Highlanders it is called dulling, or waterleaf. It is employed as food by the poor of many nations ; when well washed, it is chewed by the peasantry of Ireland without being dressed. It is nutritious, but sudorific, has the smell of violets, imparts a mucila- ginous feel to the mouth, leaving a slightly acrid taste. In Iceland the dulse is thoroughly washed in fresh water and dried in the air. AVhen thus treated it becomes covered with a white powdery substance, which is sweet and palatable ; this is mannite, (see Manna,) which Dr. Stenhouse proposes to obtain from seaweeds. " In the dried state it is used in Iceland with fish and butter, or else, by the higher classes : boiled in milk with the addition of rye flour. It is preserved packed in close casks ; a fermented liquor is produced in Kam- schatka from this seaweed, and in the north of Europe and in the Grecian Archipelago cattle are fed upon it." — Stenhouse.

Laminaria saccharina yields 12-15 percent, of mannite, wdiile the Phodomenia pal- mata contains not more than 2 or 3 per cent.

Iridcea echdis. — The fronds of this weed are of a dull purple color, flat, and succulent. It is employed as food by fishermen, either raw or pinched between hot irons, and its taste is then said to resemble roasted oysters.

Alaria escidenta. — Mr. Drummond informs us that, on the coast of Antrim, " it is often gathered for eating, but the part used is the leaflets, and not the midrib, as is commonly stated. These have a very pleasant taste and flavor, but soon cover the mouth with a tena- cious greenish crust, which causes a sensation somewhat like that of the fat of a heart or kidney."

Ulva latissima, (Broad green laver.) — This is rarely used, being considered inferior to the Porphyra laciniata, (Laciniated purple laver.) This alga is abundant on all our shores. It is pickled with salt, and sold in England as laver, in Ireland as slojce, and in Scotland as slaak. The London shops are mostly supplied with laver from the coasts of Devonshire. When stewed, it is brought to the table and eaten with pepper, butter or oil, and lemon- juice or vinegar. Some persons stew it with leeks and onions. The pepper dulse, (Lau- rencia pinnatifida,) distinguished for its pungent taste, is often used as a condiment when other seaweeds are eaten. " Tangle," (Lami.naria digitata,) so called in Scotland, is termed " red-ware " in the Orkneys, " sea-wand " in the Highlands, and " sea-girdles " in England. The flat leathery fronds of this weed, when young, are employed as food, Mr. Simmonds tells us, " There was a time when the cry of ' Buy dulse and tangle ' was as com- mon in the streets of Edinburgh and Glasgow, as is that of ' water-cresses' now in our me- tropolis."— Society of Arts' Journal.

ALKALI. 41

Laminaria potatorum. — The large sea tangle is used abundantly by the inhabitants of the Straits of Magellan and by the Fuegians. Under the name of " Bull Kelp " it is used as food in New Zealand and Van Diemen's Land. It is stated to be exceedingly nutritive and fattening.

Chondrus crispus, (chondrus, from x^ySpos, cartilage.) — Carrageen, Irish, or pearl moss. For purposes of diet and for medicinal uses, this alga is collected on the west coast of Ire- land, washed, bleached by exposure to the sun, and dried. It is not unfrequently used in Ireland by painters and plasterers as a substitute for size. It has also been successfully applied, instead of isinglass, in making of blanc-mange and jellies ; and in addition to its use in medicine, for which purpose it was introduced by Dr. Todhunter, of Dublin, about 1S31, a thick mucilage of carrageen, scented with some prepared spirit, is sold as bando- line, fixature, or clysphitique, and it is employed for stiffening silks. According to Dr. Davy, carrageen consists of

Gummy matter, . . . . . 28 -5

Gelatinous matter, . . . . . 49-0

Insoluble matter, ...... 22-5

100-0

Plocaria Candida. — Ceylon moss ; edible moss. This moss is exported from the islands of the Indian Archipelago, forming a portion of the cargoes of nearly all the junks. It is stated by Mr. Crawford, in his " History of the Indian Archipelago," that on the spots where it is collected, the prices seldom exceed from 5s. 8d. to *7s. 6<£ per cwt. The Chinese use it in the form of a jelly with sugar, as a sweetmeat, and apply it in the arts as an excel- lent paste. The gummy matter which they employ for covering lanterns, varnishing paper, &c, is made chiefly from this moss.

This moss, as ordinarily sold, appears to consist of several varieties of marine produc- tions, with the Plocaria intermixed.

The Agar-Agar of Malacca belongs to this variety ; and probably seaweeds of this character are used by the Salangana or esculent swallow in constructing their nests, which are esteemed so great a delicacy by the Chinese. The plant is found on the rocks of Pulo Ticoos and on the shores of the neighboring islands. It is blanched in the sun for two days, or until it is quite white. It is obtained on submerged banks in the neighborhood of Macassar, Celebes, by the Bajow-laut, or sea-gipsies, who send it to China. It is also col- lected on the reefs and rocky submerged ledges in the neighborhood of Singapore. Mr. Montgomery Martin informs us that this weed is the chief staple of Singapore, and that it produces in China from six to eight dollars per pecul in its dry and bulky state. The har- vest of this seaweed is from 6,000 to 12,000 peculs annually, the pecul being equal to 100 catties of 1-333 lbs. each.

Similar to this, perhaps the same in character, is the Agal-Agal, a species of seaweed. It dissolves into a glutinous substance. Its principal use is for gumming silks and paper, as nothing equals it for paste, and it is not liable to be eaten by insects. The Chinese make a beautiful kind of lantern, formed of netted thread washed over with this gum, and which is extremely light and transparent. It is brought by coasting vessels to Prince of Wales Island, and calculated for the Chinese market. — Oriental Commerce.

ALIMENT. (Alimentum, from alo, to feed.) The food necessary for the human body, and capable of maintaining it in a state of health.

1. Nitrogenous substances are required to deposit, from the blood, the organized tissue and solid muscle ;

2. And carbonaceous, non-nitrogenous bodies, to aid in the processes of respiration, and in the supply of carbonaceous elements, as fat, &c., for the due support of animal heat.

For information on these substances, consult Liebig's " Animal Chemistry," the investi- gations of Dr. Lyon Playfair, and Dr. Eobert Dundas Thompson's " Experimental Researches oaFood," 1846.

ALKALI. A term derived from the Arabians, and introduced into Europe when the Mahometan conquerors pushed their conquests westward. Al, el, or ul, as an Arabic noun, denotes " God, Heaven, Divine." As an Arabic particle, it is prefixed to words to give them a more emphatic signification, much the same as our particle the ; as in Alcoran, the Koran ; alehymisi, the chemist.

Kali was the old name for the plant producing potash, (the glasswort, so called from its use in the manufacture of glass,) and alkali signified no more than the kali plant. Potash and soda were for some time confounded together, and were hence called alkalis. Ammonia, which much resembles them when dissolved in water, was also called an alkali. Ammonia was subsequently distinguished as the volatile alkali, potash and soda being fixed alkalis: Ammonia was also called the animal alkali. Soda was the mineral alkali, being derived from rock salt, or from the ocean ; and potash received the name of vegetable alkali, from its source being the ashes of plants growing upon the land. Alkalis are characterized by

42

ALKALIS, ORGAMC.

being very soluble in water, by neutralizing the strongest acids, by turning brown vegetable yellows, and to green the vegetable reds and blues.

Some chemists classify all salifiable bases under this name.

In commercial language, the term is applied to an impure soda, the imports of which were —

Imports.

Alkali and Barilla.	1S53.	1S54.	1855.	1856.
Portugal Spain Canary Islands .... Greece Two Sicilies Egypt --.--- Peru Other parts Total ....	Cwts. 2,540 15,220 9,240 7,920 2,040 20	Cwts. 5,480 7,840 3,160 2,400 4,800 1,900 160	Cwts. 1,000 2,520 10,640 500	Cwts. 3,560 3,480 9,320 4,760 80
86,980	25,740	14,660	21,200 i

Our Exports during the same periods being as follows : —
Alkali and Barilla.	1853.	1S54.	1855.	1856.
	Cwts.	Cwts.	Cwts.	Cwts.
Kussia — Northern Ports	13,845	4,208	-	82,667
" Southern Ports	7,079	200
Sweden	7,804	13,478	14,908	14,924
Denmark . - - - -	39,366	40,329	52,721	39,417
Prussia ------	82,735	96,839	104,111	85,364
Hanover	13,989	9,715	18,871	25,029
Ha rise Towns ....	97,939	93,774	77,648	83,385 ■
Holland	112,370	112,023	114,068	121,645
Belgium ......	10,069	16,837	21,293	39,650
				9,972
Spain and the Canaries - - -	-	0,921	4,090	11,042
				7,326
Austrian Territories ...	28,957	21,023	22,587	27,124
Turkev	-	-	13,010	9,142
Australia	49,377	52,390	19,882	87,790
British North America -	12,271	14,344	16,102	25,520
United States ....	550,735	559,942	494,254	723,089
Brazil ------	12,281	20,153	23,805	26,149
Chili		10,392	5,185
Other Countries - Total .---	29,771	33,747	42,469	39,666
1,070,624	1,100,315	1,045,004	1,405,901

ALKALIS, ORGANIC. During the last few years the number of organic alkaloids has so greatly increased, that a considerable volume might be devoted to their history. There are, however, only a few which have become articles of commerce. The modes of prepa- ration will be given under the heads of the alkalis themselves. The principal sources from whence they are obtained are the following :■ — 1. The animal kingdom. 2. The vegetable kingdom. 3. Destructive distillation. 4. The action of potash on the cyanic and cyanuric ethers. 5. The action of ammonia on the iodides, &e., of the alcohol radicals. 6. The action of reducing agents on nitro-compounds. The principal bases existing in the animal kingdom are creatine and sarcosine. The vegetable kingdom is much richer in them, and yields a great number of organic alkalis, of which several are of extreme value in medi- cine. Modern chemists regard all organic alkalis as derived from the types ammonia or oxide of ammonium. Their study has led to results of the most startling character. It has been found that not only may "the hydrogen in ammonia and oxide of ammonium be replaced by metals and compound radicals without destruction of the alkaline character, but even the nitrogen may be replaced by phosphorus or arsenic, and yet the resulting com- pounds remain powerfully basic. In studying the organic bases, chemists have constantly

ALKALIMETRY.

43

had in view the artificial production of the bases of cinchona bark. It is true that this result has not as yet been attained ; but, on the other hand, bodies have been formed hav- ing so many analogies, both in constitution and properties, with the substances sought, that it cannot be doubted the question is merely one of time. The part performed by the bases existing in the juice of flesh has not been ascertained, and no special remedial virtues have been detected in them ; but this is not the case with those found in vegetables ; it is, in fact, among them that the most potent of all medicines are found — such, for example, as quinine and morphia. It is, moreover, among vegetable alkaloids that we find the sub- stances most inimical to life, for aconitine, atropine, brucine, coniine, curarine, nicotine, solanine, strychnine, &c, &c, are among their number. It must not be forgotten, how- ever, that, used with proper precaution, even the most virulent are valuable medicines. The fearfully poisonous nature of some of the organic bases, together with an idea that they are difficult to detect, has unhappily led to their use by the poisoner ; strychnine, especially, has acquired a painful notoriety, in consequence of its employment by a medical man to destroy persons whose lives he had insured. Fortunately for society, the skill of the analyst has more than kept pace with that of the poisoner ; and without regarding the extravagant assertions made by some chemists as to the minute quantities of vegetable poisons they are able to detect, it may safely be asserted that it would be very difficult to administer a fatal dose of any ordinary vegetable poison without its being discovered. Another check upon the poisoner is found in the fact that those most difficult of isolation from complex mixtures are those which cause such distinct symptoms of poisoning in the victim, that the medical attendant, if moderately observant, can scarcely fail to have his suspicions aroused.

Under the heads of the various alkaloids will be found (where deemed of sufficient importance) not merely the mode of preparation, but also the easiest method of detection. — C. G. W.

ALKALIHETER. There are various kinds of alkalimeters, but it will be more conven- ient to explain their construction and use in the article on Alkalimetry, to which the reader is referred.

ALKALIMETRY. 1. The object of alkalimetry is to determine the quantity of caustic alkali or of carbonate of alkali contained in the potash or soda of commerce. The prin- ciple of the method is, as in acidimetry, based upon Dalton's law of chemical combining ratios — that is, on the fact that in order to produce a complete reaction, a certain definite weight of reagent is required, or, in other words, in order to saturate or completely neu- tralize, for example, one equivalent of a base, exactly one equivalent of acid must be em- ployed, and vice versa. This having been thoroughly explained in the article on Acidim- etry, the reader is referred thereto.

2. The composition of the potash and of the soda met with in commerce presents very

11

great variations ; and the value of these substances being, of course, in propor- tion to the quantity of real alkali which they contain, an easy and rapid method of determining that quantity is obviously of the greatest importance both to the manufacturer and to the buyer. The process by which this object is attained, though originally contrived exclusively for the determination of the intrinsic value of these two alkalis, (whence its name, Alkalimetry,) has since been ex- tended to that of ammonia and of earthy bases and their carbonates, as will be shown presently.

3. Before, however, entering into a description of the process itself, we will give that of the instrument employed in this method of analysis, which instru- ment is called an alkalimeter.

4. The common alkalimeter is a tube closed at one end, (see figure in mar- gin,) of about f of an inch internal diameter, about 9A inches long, and is thus capable of containing 1,000 grains of pure distilled water. The space occupied by the water is divided accurately into 100 divisions, numbering from above downwards, each of which, therefore, represents 10 grains of distilled water.

5. When this alkalimeter is used, the operator must carefully pour the acid from it by closing the tube with his thumb, so as to allow the acid to trickle in drops as occasion may require ; and it is well also to smear the edge of the tube with tallow, in order to prevent any portion of the test acid from being wasted by running over the outside after pouring, which accident would, of course, render the analysis altogether inaccurate and worthless ; and, for the same rea- son, after having once begun to pour the acid from the alkalimeter by allowing it to trickle between the thumb and the edge of the tube, as above mentioned, the thumb must not be removed from the tube till the end of the experiment, for otherwise the portion of acid which adheres to it would, of course, be wasted and vitiate the result. This uncomfortable precaution is obviated in the other forms of alkalimeter now to be described.

^~z	.
H	5
-i	10
.3	15
'•%	20
-	35
=	30
S	ss
-5	40
=	4S
_=	50
£	55
_=	60
-	03
-=	70
£	75
-i	3D
£	ES
	90
1	S5
K-J	100

44

ALKALIMETRY.

lc

f3?

6. That represented in fig. 12 is Gay-Lussac's alkalimeter ; it is a glass tube about 14 inches high, and \ an inch in diameter, capable of holding more than 1,000 grains of dis- tilled water ; it is accurately graduated from the top down- wards into 100 divisions, in such a way that each division may contain exactly 10 grains of water. It has a small tube, 6, communicating with a larger one, which small tube is bent and bevelled at the top, c. This very ingenious instrument, known also under the name of " burette" and " pouretfi was contrived by Gay-Lussac, and is by far more convenient than the common alkalimeter, as by it the test acid can be unerringly poured, drop by drop, as wanted. The only drawback is the fragility of the small side-tube, 6, on which account the com- mon alkalimeter, represented in fig. 11 is now generally used, especially by workmen, because, as it has no side-tube, it is less liable to be broken ; but it gives less accurate results, a portion of the acid being wasted in various ways, and it is, besides, less manageable. Gay-Lussac's " burette " is there- fore preferable ; and if melted wax be run between the space of the large and of the small tube, the instrument is rendered much less liable to injury ; it is generally sold with a separate wooden foot or socket, in which it may stand vertically.

7. The following form of alkalimeter, {fig. 13,) which I contrived several years ago, will, I think, be found equally delicate but more convenient still than that of Gay-Lussac. It consists of a glass tube, a, of the same dimensions, and grad- uated in the same manner as that of Gay-Lussac ; but it is provided with a glass foot, and the upper part, b, is shaped like the neck of an ordinary glass bottle ; c is a bulb blown from a glass tube, one end of winch is ground to fit the neck, b, of the alkalimeter, like an ordinary glass stopper. This bulb is drawn to a capillary point at d, and has a somewhat large opening at e. With this instrument the acid is perfectly under the control of the operator, for the globular joint at the top enables him to see the liquor before it actually begins to drop out, and he can then regulate the pouring to the greatest nicety, whilst its more substantial form renders it much less liable to accidents than that of Gay-Lussac ; the glass foot is extremely convenient, and is at the same time a great additional security. The manner of using it will be described further on.

8. Another alkalimeter of the same form as that which I have just described, except that it is all in one piece, and has no globular enlargement, is represented in fig. 14. Its con- struction is otherwise the same, and the results obtained are equally

delicate ; but it is less under perfect control, and the test acid is very liable to rim down the tube outside : this defect might be easily remedied by drawing the tube into a finer and more delicate point, instead of in a thick, blunted projection, from which the last drop cannot be detached, or only with difficulty, and imperfectly. A glass foot would, moreover, be an improvement.

9. With Schuster's alkalimeter, (represented in fig. 15,) the strength of alkalis is determined by the weight, not by the measure, of the acid employed to neutralize the alkali ; it is, as may be seen, a small bottle of thin glass, having the form of the head of the alkalimeter repre- sented in fig. 13. We shall describe further on the process of analysis with this alkalimeter.

10. There are several other forms of alkalimeter, but those which have been alluded to are almost exclusively used, and whichever of them is employed, the process is the same — namely, pouring carefully an acid of a known strength into a known weight of the alkali under examination, until the neutralizing point is obtained, as will be fully explained presently.

11. Blue litmus-paper being immediately red- dened by acids is the reagent used for ascertaining the exact point of the neutralization of the alkali to be tested. It is prepared by pulverizing one part of commercial litmus, and digesting it in six parts of cold water, filtering, and dividing the blue liquid into two equal portions, adding carefully to one of the portions, and one drop at a time, as much very dilute sulphuric acid as is sufficient to impart to it a slight red color, and pouring the portion so treated into the second portion, which is intensely blue, and stirring the

15

\ r
.=
4	13
.=	:C
>=
■=	"
_1	40
-1	50
M	CO
-f	70
-|	80
|	90
vJ*	100

ALKALIMETEY.

45

whole together. The mixture so obtained is neutral, and by immersing slips of white blot- ting-paper into it, and carefully drying them by hanging them on a stretched piece of thread, an exceedingly sensitive test paper of a light blue color is