This section is from the book "Materia Medica And Therapeutics Inorganic Substances", by Charles D. F. Phillips. Also available from Amazon: Materia medica and therapeutics.
Is an impure dilute acetic acid, derived from alcohol. In France it is made from wine, and is stronger than the English vinegar, which is obtained from a fermenting infusion of malt exposed freely to air. The sugar it contains is first changed into alcohol, which by further oxidation (under the influence of a fungus found in the solution) is transformed into acetic acid; thus C2H6O + O2 becomes C2H1O2 + H1O, the acid being derived from the alcohol by the substitution of one atom of oxygen for two of hydrogen.
Vinegar has a sp. gr. of 1.017 to 1.019, is usually brown in color, and has a distinctive odor, due probably to a minute quantity of acetic ether: it contains 4.6 per cent. of anhydrous acetic acid. It is liable to become mouldy if exposed long to the air, and in order to prevent this, a little sulphuric acid is commonly added: 1/1000 part by weight is allowed by law.
The dilute acid is readily absorbed by the stomach, and combines in the blood, to some extent, if not wholly, with soda salts to form acetate of soda; like other salts of vegetable acids this is ultimately eliminated in the urine as a carbonate. The acetate of soda was one of the first salts with which the decomposition was verified by Wohler (1824).
Glacial acetic acid is a caustic, and, applied to the ordinary skin, causes redness, pain, and sometimes vesication or even inflammation of the cutis and subjacent tissue. The diluted acids exert a moderately irritant, or simply a cooling astringent effect, according to the degree of dilution, of continuance of application, friction, etc. Mucous membranes are blanched by it.