Acetic acid exists in the juice of some vegetables, but is not extracted for use. It is officinal in five forms; namely, the glacial acetic acid, which is the strongest, the strong acetic acid, the diluted acid, vinegar, and distilled vinegar. For internal use vinegar is generally preferred. I shall first describe, so far as may be deemed necessary, these several forms, and afterwards treat of their applications conjointly.

1. Vinegar

Acetum. U.S., Br. - This is the product of the acetous fermentation, by which alcohol in dilute solution is converted into acetic acid, through the agency of some azotized substance acting as a ferment, and of a temperature between 75° and 90° F. All saccharine juices or solutions, which by the vinous fermentation become alcoholic liquids, may, by the continued influence of heat and a ferment, be changed into vinegar. In France, vinegar is usually thus made from wines, in Great Britain from malt liquor, and in the United States from cider; and the strength and flavour vary, according to the character of the liquid from which it is prepared. Not unfrequently, also, vinegar is made from artificial mixtures of water and saccharine matter, with the addition of a ferment.


Vinegar fit for internal use is of variable colour, from a very pale yellow to a deep reddish-brown. It has an agreeable peculiar odour, and a sharp, acid taste. If kept long exposed to the air, it is decomposed. The ingredient on which it depends for its medical properties is acetic acid, besides which it contains various organic and saline substances in small proportion, some of which serve to qualify agreeably its odour and taste. It has the property, in some degree, of preserving organic matter from decomposition, and is often used for this purpose in pickling. To increase its apparent strength, sulphuric acid is not unfrequently added. This may be detected by boiling the liquid with chloride of calcium, which throws down any free sulphuric acid as sulphate of lime, without affecting the small proportion of sulphates contained in the vinegar. When used medicinally, it should be free from this impurity, as well as from copper and lead, sometimes imparted to it by the vessels in which it is prepared.

2. Distilled Vinegar

Acetum Deslillatum. U.S. - This is prepared by simply distilling common vinegar; a portion containing the impurities being left behind in the retort. It is a limpid, colourless liquid, having the acetous odour and taste, but less agreeable to the palate than the un-distilled. The vinegar is deprived, in the process, of its solid constituents, but not entirely of volatile organic impurity. The preparation is of variable strength, corresponding with that of the liquid from which it was obtained. Distilled vinegar is used almost exclusively in pharmacy, being preferred to the common as a menstruum, on account of its greater purity.

3. Acetic Acid

Acidum Aceticum. U.S., Br. - Acidum Pyrolig-neum. Ed. - As directed by the U. S. and British Pharmacopoeias, this is not pure acetic acid, as it contains a considerable proportion of water. it is generally prepared from the pyroligneous acid, or impure empyreumatic vinegar obtained by the destructive distillation of wood. With this liquid there is first made an impure acetate of soda, which, having been purified and crystallized, is exposed to distillation with strong sulphuric acid. The acetic acid comes over, with the water of crystallization of the acetate and the combined water of the sulphuric acid, leaving sulphate of soda in the retort.


The acetic acid of the U. S. Pharmacopoeia is a colourless liquid, very volatile, with a pungent acetous odour, and an extremely sour and sharp taste. it combines readily with water and alcohol. Heat volatilizes it entirely. it has the sp. gr. 1.047, and contains about 36 per cent. of monohydrated or glacial acetic acid, which is the strongest employed.

4. Diluted Acetic Acid

Acidum Aceticum Dilutum. U. S., Br. - This is made, according to both Pharmacopoeias, by simply mixing one part by measure of officinal acetic acid with seven parts of water. it is intended to represent distilled vinegar, to which it is preferred for pharmaceutical use, on account of its greater purity, and more uniform strength.

5. Glacial Acetic Acid

Acidum Aceticum Glaciale. Br. - Monohydrated Acetic Acid. - This is prepared, according to the Br. Pharmacopoeia, by distilling a mixture of acetate of soda, previously heated so as to drive off its water of crystallization, and sulphuric acid; but it is more commonly prepared from acetate of lead by first heating it to drive off its water, and then decomposing it either with dry muriatic acid gas, or by strong sulphuric acid. it is a colourless liquid, similar to the preceding, but much stronger, and quite insupportable to the taste. its sp. gr., as officinally stated, is 1.065. At the temperature of 40° F. it solidifies. it contains 1 equivalent of pure acetic acid and 1 of water. The pure acid contains 4 eqs. of carbon, 3 of hydrogen, and 3 of oxygen.

Effects of Acetic Acid on the System. Acetic acid, in all its forms, is locally stimulant, and in its effects upon the system an arterial sedative. in the form of vinegar, diluted so as to be agreeable as a drink, it sharpens the appetite, and promotes digestion by its direct influence on the stomach. After absorption, it lessens the frequency and force of the pulse, and the temperature of the body, and often promotes the secretory functions, especially that of the kidneys. Sometimes also it operates as a diaphoretic and laxative. if largely taken and long continued, it irritates the stomach and bowels; diminishing the appetite, disturbing digestion, and causing not unfrequently nausea and diarrhoea. Under the same circumstances, it lowers the organic functions of the system generally, impairing nutrition, depraving the blood, producing anaemia and emaciation, and ultimately, it is said, inducing a condition analogous to the scorbutic.