Vinegar. This is the second state in which the saccharine juices of vegetables appear in consequence of a spontaneous fermentation, in a heat of about 80° of Fahrenheit. In the first it becomes a wine; but a saccharine substance seems to be the principle, from which spirit is mostly formed, and mucilage that of vinegar. In the general subjects of fermentation they are united, and the acetous follows the vinous state. Should gluten predominate in the mixture, ammonia is soon discoverable, and the liquor turns putrid. In the acetous fermentation, much air is absorbed, which is apparently oxygen. See Fermentation.

Acetous acid may be formed in other ways, independent of fermentation. It is separated from many-vegetable substances by distillation. Water and carbonic acid gas are at the same time raised, and charcoal deposited. The action of nitric acid on many vegetable substances, particularly gum and farina, also produces it with the same residuum of charcoal, and exhalation of carbonic acid gas and water. This acid also appears in some changes where putrefaction is apparently- going on; as in the animal economy, where the urea is separated from the urine. Acetated lead produced from this acid, and the metal, forms a curious subject of speculation. By means of the lead it appears to regain its original state of a saccharine matter; for this substance may be fermented, again produce a vinous spirit, and ultimately again vinegar. See Neumann's Chemistry.

Vegetable liquors, in proportion to the quantity of Their saccharine parts, ferment into a weaker or stronger kind of wine; a second fermentation forms vinegar.

When malt liquor becomes acid, it is called allicar, Allegar. It is not so proper either for medical use, or preserving pickles, as the wine vinegar; for it abounds too much with mucilage, which is productive of mam-disadvantages; yet this is the only vinegar that we procure in England.

If vinegar be distilled with a heat not exceeding that of boiling water, it yields first a phlegmatic liquor (which is a spirit slightly vinous); then a slightly acid one, which is succeeded by stronger acids, till the matter remaining becomes thick as honey; if now it is urged with a greater heat, an empyreumatic oil ascends, and a penetrating acid spirit, tainted with the ill smell and yellow colour of the oil; and at last there remains a black coal, which, when burnt into white ashes, yields a considerable proportion of fixed alkaline salt.

By distillation, vinegar is separated from its mucilage, tartar, etc. Its specific gravity is then reduced from 1.0135 or 1.0251 (for it generally varies) to 1.0005. By boiling a few minutes, it keeps a long time with little change.

The stronger and more spiritous the wine, the stronger is the vinegar into which it is converted. Geoffroy says, that vinegars made of the German and French wines saturate from one-fortieth to one-twelfth of their weight of fixed alkaline salt.

Vinegar is mixed with the mineral acids by some fraudulent dealers, and the vitriolic, as the cheapest, is most commonly employed. The slightest portion may be detected, by adding a solution of muriated barytes, or a larger, by a saturated solution of chalk. In either case, a white sediment is deposited. Lead is sometimes accidentally present, and may be discovered by the liquor probatorius. See Liquor Proba-tojrius.

The fermentation which changes wine into vinegar gives the latter several properties extremely different from those of the former, which are well known. Vinegar is ultimately decomposed by nitric acid, or by fire, when combined with fixed alkali to repress its volatility.- It is then found to consist of carbone, hydro-gen, and oxygen, but the proportions are not known. It is concentrated by freezing; but the purest acetous acid freezes at about 22° of Fahrenheit, and by distilling it when combined with powdered charcoal. For its affinities, see Elective attractions.

Vinegar dissolves animal earths, if not very much mixed with gelatinous matter; the earth of alum, and calcareous earths; it oxidates several metallic substances, as zinc, iron, copper, nickel, tin, and lead. It combines with earths, alkalis, and metallic oxides; it dissolves the vegetable inspissated juices, and extracts the virtues of many plants; to many of which it seems to impart additional power, particularly to the onion tribe. In inflammatory and putrid diseases, in many instances, its efficacy is considerable: in ardent fevers it is an useful antiphlogistic and sudorific: in putrid disorders it is a preservative and restorer, fainting, lethargic, and hysteric paroxysms are much relieved by it, if applied to the nose and mouth; even in many instances more than by volatile alkaline spirits, or fetid gums. In the miliary fever it is a powerful assistant. The vegetable acid has a peculiar power in restoring sweetness to putrid bile; and that obtained from the fresh vegetable fruits is more useful than the mineral acids. Besides, when a putrid colluvies is lodged in the first passage, this acid gently tends to solicit its discharge by stool; an advantage not to be expected from the mineral tribe.

Externally applied, vinegar is a powerful resolvent and relaxant. When applied to any sensible membrane, it acts as an astringent; and, more or less diluted with water, is an excellent gargle for an inflamed throat.

and for an injection to moderate the fluor albus. See Acida.

It has been lately recommended in burns, whether there is a loss of substance or not. The burnt part is to he bathed in vinegar, till the pain ceases; then a common poultice with finely powdered chalk strewed on it is to be applied. This poultice at first must be changed every four hours, and afterwards two or three times a day. When there is no loss of substance, the vesicles arc filled with a coagulated fluid, under which the skin soon heals. As a cooling application in bruises, its use is well known; and it is frequently applied in its cold state to the nose in cases of haemorrhage. In maenorr-hagia, particularly the profluvia after parturition, applied cold to the loins and abdomen, it is very serviceable. Chilblains are also often relieved, corns and galls softened by it.

An imprudent use of vinegar is not without considerable inconveniences; large and frequent doses produce leanness and an atrophy; when taken to excess, to reduce a corpulent habit, tubercles in the lungs and a consumption have been the consequence: young children, old people, those whose circulation is languid, vital heat defective, and digestion weak, should perhaps be sparing in its use.

The dose, according to the different circumstances of the case requiring it, and the constitution of the patient, may be from ss. to iij.

See the Dictionary of Chemistry, translated from the French of M. Macquer, edit. 2, article Vinegar. Cul-len's Mat. Med. Chaptal's Chemistry, vol. iii. 268. Thompson's Chemistry, 2d edit. Parkinson's Chemical Pocket-book.