An acid liquid, prepared from malt and unmalted grain by the acetous fermentation.

Characters. - A liquid of a brown colour and peculiar odour.

Impurities. - A little sulphuric acid added to it is said to make it keep better. Too much may be fraudulently added in order to increase its acidity. Lead from the vessels in which it is kept.

Tests. - If ten minims of solution of chloride of barium be added to a fluid ounce of the vinegar, and the precipitate, if any, be separated by filtration, a further addition of the test will give no precipitate (limit of sulphuric acid). Sulphuretted hydrogen causes no change of colour (absence of lead).

Dose. - 1 to 2 fluid drachms.

Preparation in which Vinegar is used. Emplastrum Saponis Fuscum.

Action and Uses. - When applied externally to the skin, glacial acetic acid causes the formation of a large bleb. It is used to destroy warts and corns, and is sometimes employed as a vesicant in cases of kidney-disease, where danger is apprehended from the use of cantharides. When the vapour of it is sniffed up the nose, it causes reflex contraction of the blood-vessels, and raises the blood-pressure. It is therefore useful in lessening drowsiness and preventing syncope, or arousing patients from it (pp. 194 and 265).

Dilute acetic acid is applied to the skin in cases of headache, and is used to sponge the surface and check perspiration when too profuse. It checks bleeding, and may be used to stop oozing from leech-bites, or to wash out the mouth after the extraction of a tooth, and, when sniffed up the nose, sometimes arrests epistaxis. It is occasionally employed in the form of an enema to destroy ascarides.

When applied either alone or mixed with proof spirit on a napkin to the vulva it is sometimes very useful in checking menorrhagia (vide p. 351).

Acidum Phosphoricum Concentratum, B.P., Acidum