acetic acid defined in 1939 yearacetic acid - Acetic Acid;
acetic acid - Acid (C2H4O2) which occurs naturally in the juices of many plants, either in the free state or combined with potassium or calcium. Vinegar contains 4¼ to 6 per cent of acetic acid and is formed by the action of a ferment, Mycoderma aceti, on a weak alcoholic liquor. Vinegar was the only acid known to the ancients.
The acid is largely made by the destructive distillation of wood, the impure acetic acid thus obtained being known as pyroligncous acid. This acid is purified from tarry matters by neutralizing with lime and decomposing the acetate of lime thus formed by sulphuric acid. It is also extracted from pyroligneous acid by solution in ether, later evaporated, leaving the acetic acid behind.
Acetic acid is also obtained by the catalytic oxidation of alcohol with zinc oxide (the acetaldehyde thus produced being further catalytically oxidized to acetic acid); by synthesis from acetylene (another catalytic process); and by synthesis from ethylene (producing alcohol which is.oxidized to acetic acid as in the first process).
The strongest acetic acid, known as glacial acetic acid or anhydrous acetic acid, crystallises to a solid at a temperature of 62° F.
Two other strengths of acetic acid found in commerce are 33 p.c. and 4'27 p.c. acids, the weaker being approximately the strength of malt vinegar. Acetic acid in the concentrated state forms the class of salts known as acetates (q.v.). Acetic acid is also a solvent of carbon compounds in those industries which depend on organic chemistry.
near acetic acid in Knolik
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