Prep. When wood is heated in close vessels, as in iron retorts, amongst the volatile products of its destruction, a large amount of acetic acid distils over, mixed with wood spirit and various hydrocarbons; from this fluid, after redistillation, and neutralization with carbonate of soda, acetate of soda is separated by crystallization, and purified by several re-crystallizations; this salt heated with sulphuric acid and water yields acetic acid mixed with water, and forms the product under consideration.

Prop. & Comp. A colourless liquid with a very pungent odour and strong acid taste, sp. gr. 1.044 [1.047. U. S.], contains 28 per cent. of anhydrous acetic acid (C4 H3 O3); is volatile, and leaves no residue when evaporated. One fluid drachm requires for neutralization 31.5 measures of the volumetric solution of soda. It gives no precipitate with chloride of barium or nitrate of silver, has no action on strips of metallic silver, and when neutralized with ammonia is not precipitated by sulphuretted hydrogen, ammonia, or ferrocyanide of potassium; these various tests indicating a freedom from sulphuric, hydrochloric, or nitric acids, and metallic impurities, especially copper: it does not give rise to a blue colour when added gradually to an equal volume of the solution of iodate of potash, previously mixed with a little mucilage of starch. This shows the absence of sulphurous acid, which, if present, would set free iodine by deoxidizing the iodate, and the blue iodide of starch would be formed.

Of. Prep. Acidum Aceticum Dilutum. Dilute Acetic Acid. (Acetic acid, twenty fluid ounces; distilled water, one hundred and forty fluid ounces.)

The sp. gr. is 1.006. One fluid ounce requires for neutralization thirty-one measures of the volumetric solution of soda. It contains 3 1/2 per cent. of anhydrous acetic acid.

Oxymel. Oxymel. [Not officinal in U. S. P.] (Clarified honey, forty ounces; acetic acid, five fluid ounces; distilled water, five fluid ounces.)

Therapeutics. When freely diluted, acetic acid, given internally, acts as a refrigerant, but is seldom employed for this purpose. Externally, in its strong form, it is used as a rubefacient; sometimes as a vesicant and escharotic; but the glacial acid is more effective for such purposes; much diluted, it may be used to sponge the surface in fevers, also in cooling lotions. Acetic acid is more frequently employed on account of its solvent powers, than for any therapeutic value it may possess, as in Linimentum Cantharidis.

Dose. Of acidum aceticum dilutum, 1 fl. drm. to 3 fl. drm. diluted still more. Of oxymel 1 fl. drm. to 1/2 fl. oz.

Adulteration. Foreign acids and metallic impurities, as copper, detected by the above tests.