These grains are ground, mixed, and boiled, along with twenty-seven casks-full of river water, for three hours. Eighteen casks of good beer for vinegar are obtained. By a subsequent decoction, more fermentable liquid is extracted, which is mixed with the former. The whole brewing yields 3000 English quarts.

In this country, vinegar is usually made from malt. By mashing with hot water, 100 gallons of wort are extracted in less than two hours from 1 boll of malt. When the liquor has fallen to the temperature of 75° Fahr. 4 gallons of the barm of beer are added. After thirty-six hours it is racked off into casks, which are laid on their sides, and exposed, with their bung-holes loosely covered, to the influence of the sun in summer; but in winter they are arranged in a stove-room. In three months this vinegar is ready for the manufacture of sugar of lead. To make vinegar for domestic use, however, the process is somewhat different. The above liquor is racked off into casks placed upright, having a false cover pierced with holes fixed at about a foot from their bottom. On this a considerable quantity of rape, or the refuse from the makers of British wine, or otherwise a quantity of low priced raisins, is laid. The liquor is turned into another barrel every twenty-four hours, in which time it has begun to grow warm. Sometimes, indeed, the vinegar is fully fermented, as above, without the rape, which is added towards the end, to communicate flavour. Two large casks are in this case worked together, as is described long ago by Boerhaave, as follows.

"Take two large wooden vats, or hogsheads, and in each of these place a wooden grate or hurdle, at the distance of a foot from the bottom. Set the vessel upright, and on the grate place a moderately close layer of green twigs, or fresh cuttings of the vine. Then fill up the vessel with the footstalks of grapes, commonly called the rape, to the top of the vessel, which must be left quite open.

"Having thus prepared the two vessels, pour into them the wine to be converted into vinegar, so as to fill one of them quite up, and the other but half full. Leave them thus for twenty-four hours, and then VOL. J

[2]

fill up the half filled vessel with liquor from that which is quite full, and which will now in its turn only be left half full. Four-and-twenty hours afterwards repeat the same operation, and thus go on, keeping the vessels alternately full and half full during twenty-four hours, till the vinegar be made. On the second or third day there will arise in the halffilled vessel, a fermentative motion, accompanied with a sensible heat, which will gradually increase from day to day. On the contrary, the fermenting motion is almost imperceptible in the full vessel; and as the two vessels are alternately full and half full, the fermentation is by this means in some measure interrupted, and is only renewed every other day in each vessel.

"When this motion appears to have entirely ceased, even in the half filled vessel, it is a sign that the fermentation is finished; and therefore the vinegar is then to be put into casks close stopped, and kept in a cool place.

"A greater or less degree of warmth accelerates or checks this, as well as the spirituous fermentation. In France it is finished in about fifteen days, during the summer; but if the heat of the air be very great, and exceed the twenty-fifth degree of Reaumur's thermometer, (884° Fahr.) the half filled vessel must be filled up every twelve hours; because, if the fermentation be not so checked in that time, it will become violent, and the liquor will be so heated, that many of the spirituous parts, on which the strength of the vinegar depends, will be dissipated, so that nothing will remain after the fermentation but a vapid liquor, sour indeed, but effete. The better to prevent the dissipation of the spirituous parts, it is a proper and usual precaution to close the mouth of the half filled vessel, in which the liquor ferments, with a cover made of oak wood. As to the full vessel, it is always left open, that the air may act freely on the liquor it contains; for it is not liable to the same inconveniences, because it ferments but very slowly."

Good vinegar may be made from a weak sirup, consisting of 18 oz. of sugar to every gallon of water. The yeast and rape are to be here used, as above described. Whenever the vinegar (from the taste and flavour) is considered to be complete, it ought to be decanted into tight barrels or bottles, and well secured from access of air. A momentary ebullition before it is bottled is found favourable to its preservation. In a large manufactory of malt vinegar, a considerable revenue is derived from the sale of yeast to the bakers. Vinegar obtained by the preceding methods has more or less of a brown colour, and a peculiar but rather grateful smell. By dis

tillation in glass vessels the colouring matter, which resides in a mucilage, is separated, but the fragrant odour is generally replaced by an empyreumatic one. The best French wine vinegars, and also some from malt, contain a little alcohol, which comes over early with the watery part, and renders the first product of distillation scarcely denser, sometimes even less dense than water. It is accordingly rejected.Towards the end of the distillation the empyreuma increases. Hence only the intermediate portions are retained as distilled vinegar. Its specific gravity varies from 1.005 to 1.015, while that of common vinegar of equal strength varies from 1.010 to

1.025.

A crude vinegar has been long prepared for the calico printers, by subjecting wood in iron retorts to a strong red heat. The following arrangement of apparatus has been found to answer well. A series of cast-iron cylinders, about 4 feet diameter, and 6 feet long, are built horizontally in brick work, so that the flame of one furnace may play round about two cylinders. Both ends project a little from the brick work. One of them has a disc of cast-iron well fitted and firmly bolted to it, from the centre of which disc an iron tube about 6 inches diameter proceeds, and enters at a right angle the main tube of refrigeration. The diameter of this tube may be from 9 to 14 inches, according to the number of cylinders. The other end of the cylinder is called the mouth of the retort. This is closed by a disc of iron, smeared round its edge with clay-lute, and secured in its place by wedges. The charge of wood for such a cylinder is about 8 cwt. The hard woods, oak, ash, birch, and beech, are alone used. Fir does not answer. The heat is kept up during the day-time, and the furnace is allowed to cool during the night. Next morning the door is opened, the charcoal removed, and a new charge of wood is introduced. The average product of crude vinegar called pyrolignous acid is 35 gallons. It is much contaminated with tar; is of a deep brown colour; and has a sp. gr. of 1.025. Its total weight is therefore about 300 lbs. But the residuary charcoal is found to weigh no more than onefifth of the wood employed. Hence nearly one half of the ponderable matter of the wood is dissipated in incondensable gases. Count Rumford states, that charcoal is equal in weight to more than four-tenths of the wood from which it is made. And M. Clement says that it is equal to onehalf. The Count's error seems to have arisen from the slight heat of an oven to which his woed was exposed in a glass cylinder. The result now given is the experience of an eminent manufacturing chemist at Glasgow. The crude pyrolig

nous acid is rectified by a second distillation in a copper still, in the body of which about 20 gallons of viscid tarry matter are left from every 100. It has now become a transparent brown vinegar, having a considerable empyreumatic smell, and a sp. gr. of 1.013. Its acid powers are superior to those of the best household vinegar, in the proportion of 3 to 2. By redistillation, saturation with quick-lime, evaporation of the liquid acetate to dryness, and gentle torrefaction, the empyreumatic matter is so completely dissipated, that on decomposing the calcareous salt by sulphuric acid, a pure, perfectly colourless, and grateful vinegar rises in distillation. Its strength will be proportional to the concentration of the decomposing acid.

The acetic acid of the chemist may be prepared in the following modes: 1st, Two parts of fused acetate of potash with one of the strongest oil of vitriol yield, by slow distillation from a glass retort into a refrigerated receiver, concentrated acetic acid. A small portion of sulphurous acid, which contaminates it, may be removed by redistillation, from a little acetate of lead. 2d, Or 4 parts of good sugar of lead, with 1 part of sulphuric acid treated in the same way, afford a slightly weaker acetic acid. 3d, Gently calcined sulphate of iron, or green vitriol, mixed with sugar of lead in the proportion of 1 of the former to 24 of the latter, and carefully distilled from a porcelain retort into a cooled receiver, may be also considered a good economical process. Or without distillation, if 100 parts of well dried acetate of lime be cautiously added to 60 parts of strong sulphuric acid, diluted with 5 parts of water, and digested for 24 hours, and strained, a good acetic acid, sufficiently strong for every ordinary purpose, will be obtained.

The distillation of acetate of copper or of lead per se, has also been employed for obtaining strong acid. Here, however, the product is mixed with a portion of the fragrant pyro-acetic spirit, which it is troublesome to get rid of. Undoubtedly the best process for the strong acid is that first described, and the cheapest the second or third. When of the utmost possible strength its sp. gravity is 1.062. At the temperature of 50° F. it assumes the solid form, crystallizing in oblong rhomboidal plates. It has an extremely pungent odour, affecting the nostrils and eyes even painfully, when its vapour is incautiously snuffed up. Its taste is eminently acid and acrid. It excoriates and inflames the skin.

The purified wood vinegar, which is used for pickles and culinary purposes, has commonly a specific gravity of about 1.009; when it is equivalent in acid strength to good wine or malt vinegar of 1.014. It contains about of its weight of absolute acetic acid, and 12 of water. An excise duty of 4d. is levied on every gallon of vinegar of the above strength, This, however, is not estimated directly by its sp. gr. but by the sp. gr. which results from its saturation with quick-lime, The decimal number of the sp. gr. of the calcareous acetate, is nearly double that the pure wood vinegar. Thus. 1.009 in vinegar, becomes 1.018 in liquid acetate. But the vinegar of fermentation = 1.014 will become only 1.023 in acetate, from which, if 0.005 be subtracted for mucilage

of

or extractive, the remainder will agree with the density of the acetate from wood, A glass hydrometer of Fahrenheit's construction is used for finding the specific gravities. It consists of a globe about 3 inches diameter, having a little ballast ball drawn out beneath, and a stem above of about 3 inches long, containing a slip of paper with a transverse line in the middle, and surmounted with a little cup for receiving weights or poises. The experi

ments on which this instrument, called an Acetometer, is constructed, have been detailed in the sixth volume of the Journal of Science. They do not differ essentially from those of Mollerat. The following points were determined by this chemist, The acid of sp. gr. 1.063 requires 24 times its weight of crystallized subcarbonate of soda for saturation, aturation, whence M. Thenard regards it as a compound of 11 of water, and 89 of real acid in the 100 parts. Com. bined with water in the proportion of 100 to 112.2, it does not change its density, but it then remains liquid several degrees below the freezing point of water. By diluting it with a smaller quantity of water, its sp. gr. augments, a circumstance peculiar to this acid. It is 1.079, or at its maximum, when the water forms one-third of the weight of the acid. -Ann. de Chimie, tom. 66.

The following table is given by Messrs Taylor as the basis of their acetome

ter:

acid. Or by exposing vinegar to very cold air, or to freezing mixtures, its water separates in the state of ice, the interstices of

The

which are occupied by a strong acetic acid, which may be procured by draining. acetic acid or radical vinegar of the apothecaries, in which they dissolve a little camphor, or fragrant essential oil, has a specific gravity of about 1.070. It contains fully fully 1 part of water to 2 of the crystallized acid. The pungent smelling salt consists of sulphate of potash moistened with that acid. Acetic acid acts on tin, iron, zinc, copper, and nickel; and it combines readily with the oxides of many other metals, by mixing a solution of their sulphates

with that of an acetate of lead.

This acid, as it exists in the acetates of barytes and lead, has been analyzed by M. M. Gay-Lussac and Thenard, and also by Berzelius.

Gay-Lussac found 50.224 carbon, 5.629 hydrogen, and 44.147 oxygen; or, in other terms, 50.224 carbon, 49.665 of water, or

its elementary constituents, and 0.111 hy

drogen in excess.

Berzelius.-46.83 carb. 6.35 hydr. and 46.82 oxygen in the hundred parts.

Their methods are described under VEGETABLE (ANALYSIS). By saturating known weights of bases with acetic acid, and as certaining the quantity of acetates obtained after cautious evaporation to dryness, Berzelius obtained with lime (3.55) 6.5 for the prime equivalent of acetic acid, and with yellow oxide of lead 6.432. Recent researches, which will be published in a de. tailed form, induce me to fix the prime of

acetic acid at 6.63. It would seem to con

sist, by Berzelius's analysis, of

3 Primes of hydrogen 3.75 6.2 carbon 30. 46.9 oxygen 30. 46.9

4 3

63.75 100.0

The quantity of hydrogen is probably much underrated. Acetic acid dissolves resins, gum-resins, camphor, and essential

om the

relieve nervous headaches, fainting fits, or sickness occasioned by crowded rooms. In a slightly dilute state, its application has been found to check hemorrhagy from nostrils. Its anticontagious powers are now little trusted to. It is very largely used in calico printing. Moderately rectified pyrolignous acid has been recommended for the preservation of animal food; but the empyreumatic taint it communicates to bodies immersed in it, is not quite removed by their subsequent ebullition in water. See Acid, (Pyrolignous).

Acetic acid and common vinegar are sometimes fraudulently mixed with sul

phuric acid to give them strength. This adulteration may be detected by the addition of a little chalk, short of their saturation. With pure vinegar the calcareous base forms a limpid solution, but with sulphuric acid a white insoluble gypsum. Muriate of barytes is a still nicer test. British fermented vinegars are allowed by law to contain a little sulphuric acid, but the quantity is frequently exceeded. Copper is discovered in vinegars by supersaturating them with ammonia, when a fine blue colour is produced; and lead by sulphate of soda, hydrosulphurets, sulphuretted hydrogen, and gallic acid. None of these should produce any change on genuine vinegar. See LEAD.*

* ACID (OXY-ACETIC). Acetic acid dissolves deutoxide of barium without effervescence. By precipitating the barytes with sulphuric acid, there remains an oxygenized acid, which, being saturated with potash, and heated, allows a great quantity of oxygen gas to escape. There is disengaged at the same time a notable quantity of carbonic acid gas. This shows that the oxygen, when assisted by heat, unites in part with the carbon, and doubtless likewise with the hydrogen of the acid. It is in fact acetic deutoxide of hydrogen.

Salts consisting of the several bases, united in definite proportions to acetic acid, are called acetates. They are characterized by the pungent smell of vinegar, which they exhale on the affusion of sulphuric acid; and by their yielding on distillation in a moderate red heat a very light, odorous, and combustible liquid called pyro-acetic (SPIRIT); which see. They are all soluble in water; many of them so much so as to be uncrystallizable. About 30 different acetates have been formed, of which only a very few have been applied to the uses of life.*

The acetic acid unites with all the alkalis and most of the earths, and with these bases it forms compounds, some of which are crystallizable, and others have not yet been reduced to a regularity of figure. The salts it forms are distinguished by their great solubility; their decomposition by fire, which carbonizes them; the spontaneous alteration of their solution; and their decomposition by a great number of acids, which extricate from them the acetic acid in a concentrated state. It unites likewise with most of the metallic oxides.

With barytes the saline mass formed by the acetic acid does not crystallize; but, when evaporated to dryness, it deliquesces by exposure to air. This mass is not decomposed by acid of arsenic. By spontaneous evaporation, however, it will crystallize in fine transparent prismatic needles, of a bitterish acid taste, which do

not deliquesce when exposed to the air, but rather effloresce.

With potash this acid unites, and forms a deliquescent salt scarcely crystallizable, called formerly foliated earth of tartar, and regenerated tartar. The solution of this salt, even in closely stopped vessels, is spontaneously decomposed: it deposites a thick, mucous, flocculent sediment, at first gray, and at length black; till at the end of a few months nothing remains in the liquor but carbonate of potash, rendered impure by a little coaly oil.

With soda it forms a crystallizable salt, which does not deliquesce. This salt has very improperly been called mineral foliated earth. According to the new nomenclature it is acetate of soda.

The salt formed by dissolving chalk or other calcareous earth in distilled vinegar, formerly called salt of chalk, or fixed vegetable sal ammoniac, and by Bergman calx acetata, has a sharp bitter taste, appears in the form of crystals resembling somewhat ears of corn, which remain dry when exposed to the air, unless the acid has been super-abundant, in which case they deliquesce. By distilling without addition, the acid is separated from the earth, and appears in the form of a white, acid, and inflammable vapour, which smells like acetic ether, somewhat empyreumatic, and which condenses into a reddish brown liquor.

This liquor, being rectified, is very volatile and inflammable: upon adding water it acquires a milky appearance, and drops of oil seem to swim upon the surface. After the rectification, a reddish brown liquor remains behind in the retort, toge. ther with a black thick oil. When this earthy salt is mixed with a solution of sulphate of soda, the calcareous earth is precipitated along with the sulphuric acid; the acetic acid uniting with the soda, makes a crystallizable salt, by the calcination of which to whiteness, the soda may be obtained. This acetic calcareous salt is not soluble in spirit of wine.

Of the acetate of strontian little is known, but that it has a sweet taste, is very soluble, and is easily decomposed by a strong heat.

The salt formed by uniting vinegar with ammonia, called by the various names of spirit of Mindererus, liquid sal ammoniac, acetous sal ammoniac, and by Bergman alkali volatile acetatum, is generally in a liquid state, and is commonly believed not to be crystallizable, as in distillation it passes entirely over into the receiver. It nevertheless may be reduced into the form of small needle-shaped crystals, when this liquor is evaporated to the consistence of a sirup.

Westendorf, by adding his concentrated vinegar to carbonate of ammonia, obtained a pellucid liquid, which did not crystallize; and which by distillation was totally expelled from the retort, leaving only a white spot. In the receiver, under the clear fluid, a transparent saline mass appeared, which being separated from the fluid, and exposed to gentle warmth, melted and threw out abundance of white vapours, and in a few minutes shot into sharp crystals resembling those of nitre. These crystals remain unchanged while cold, but they melt at 120° and evaporate at about 250°. Their taste at first is sharp and then sweet, and they possess the general properties of neutral

salts.

Glucine is readily dissolved by acetic acid. This solution, as Vauquelin informs us, does not crystallize; but is reduced by evaporation to a gummy substance, which slowly becomes dry and brittle; retaining a kind of ductility for a long time. It has a saccharine and pretty strongly astringent taste, in which that of vinegar however, is distinguishable.

Yttria dissolves readily in acetic acid, and the solution yields by evaporation crystals of acetate of yttria. These have commonly the form of thick six-sided plates, and are not altered by exposure to the air.

Alumine, obtained by boiling alum with alkali, and edulcorated by digesting in an alkaline lixivium, is dissolved by distilled vinegar in a very inconsiderable quantity. A considerable quantity of the earth of alum, precipitated by alkali, and edulcorated by hot water in Margraff's manner, is soluble in vinegar, and a whitish saline mass is then obtained, which is not crystallizable. From this mass a concentrated acetic acid may be obtained by distillation. Or to a

boiling solution of alum in water gradually

add a solution of acetate of lead till no further precipitate ensues. The sulphate of lead having subsided, decant the supernatant liquor, evaporate, and the acetate of alumine may be obtained in small needleshaped crystals, having a strong styptic and acetous taste. This salt is of great use in dyeing and calico printing. See ALUMINA. Acetate of zircone may be formed by pouring acetic acid on newly precipitated zircone. It has an astringent taste. It does not crystallize; but, when evaporated to dryness, forms a powder, which does not attract moisture from the air. It is very soluble both in water and alcohol; and is

not so easily decomposed by heat as nitrate of zircone.

The acetic acid has no action upon siliceous earth; for the needle-shaped crys tals observed by Durande in a mixture of vinegar with the earth precipitated from a liquor of flints, do not prove the solubility of siliceous earth, as Leonhardi observes.

Concerning the action of vinegar on al-.. cohol, see ETHER. This acid has no effect upon fat oils, except that when distilled together, some kind of mixture takes place, as the Abbé Rozier observes. Neither does distilled vinegar act upon essential oils; but Westendorf's concentrated acid dissolved about a sixth part of oil of rosemary, or one halfits weight of camphor; which latter solution was inflammable; and the camphor was precipitated from it by adding water. Vinegar dissolves the true gums, and partly the gum-resins, by means of digestion. Boerhaave observes, that vinegar by long boiling dissolves the flesh, cartilages, bones, and ligaments of animals.

ACID. (AMNIOTIC). On evaporating the liquor amnii of the cow to one-fourth, Vauquelin and Buniva found, that crystals form in it by cooling. These are contaminated by a portion of extractive matter, from which they may be freed by washing with a very small quantity of water. These crystals are white and shining, slightly acid to the taste, redden litmus paper, and are a little more soluble in hot than cold water. They are likewise soluble in alcohol. On ignited coals they swell, turn black, give out ammonia and prussic acid, and leave a bulky coal. With the alkalis this acid forms very soluble salts, but it does not decompose the carbonate without the assistance of heat. It does not precipitate the earthy salts, or the nitrates of mercury, lead, or silver. The acids precipitate it from its combinations with alkalis in a white crystaline powder. Whether it exist in the amniotic liquor of any other animal is not known.

ACID (ARSENIC). The earlier chemists were embarrassed in the determination of the nature of the white sublimate, which is

obtained during the roasting of cobalt and other metallic ores, known in commerce by the name of arsenic: its solubility in water, its power of combining with metals in their simple state, together with other apparently heterogeneous properties, rendered it difficult to determine whether it ought to be classed with metals or salts. Subsequent discoveries have shown the relation it bears to both. When treated with combustible matter, in close vessels, it sublimes in the metallic form, (See ARSENIC); combustion, or any analogous process, converts it into an oxide; and when the combustion is carried still further, the arsenical basis becomes itself converted into an acid.