Acetic Acid
2 of the 7 encyclopedias on this shelf carry an entry for Acetic Acid. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
the acid which imparts sourness to vinegar, vinegar being simply acetic acid diluted, tinged with color and slightly mingled with other impurities. The formula of acetic acid is C₂H₂O(OH), or HO.CO, CH } or CH}0 = methyl-formic acid. It is formed by the acetous fermentation of alcohol. Acetic acid is a monatomic monobasic acid. Its salts are called acetates. A molecule of acetic acid can also unite with normal acetates like water of crystallization. Its principal salts are those of potassium, sodium, and ammonium, a solution of which is called spiritus mindereri. The acetates of barium and calcium are very soluble. Aluminum acetate is used in dyeing. Lead acetate is called sugar of lead, from its sweet taste. It dissolves in 1½ parts of cold water; it also dissolves oxide of lead, forming a basic acetate of lead. Basic cupric acetate is called verdigris. Acetic acid below 15.5° forms colorless transparent crystals (glacial acetic acid), which melt into a thin, colorless, pungent, strongly acid liquid, soluble in alcohol, ether, and water. It boils at 118°. Its vapor is inflammable. Pyroligneous acid is impure acetic acid, formed by the destructive distillation, at red heat, of dry hard wood, as oak and beech. ACETIC ETHERS [example, ethyl acetate, CHO}0] C2H5 are formed by replacing the typical Huse among cyclists. In some of the lamps, in acetic acid by a radical of an alcohol, as ethyl, etc. Ethyl acetate is a fragrant liquid, sp. gr. 0.890, boils at 74°; methyl acetate boils at 56°.
The Encyclopedia of Founding (1892)
If vinous fermentation is not checked in due time, it passes at once to the stage of acetous fermentation, and the liquid becomes sour; oxygen is absorbed, and the alcohol converted into vinegar, or acetic acid. See PITCH.