1 560,385,578 gallons.

2 292,140,249 gallons.

The several tar acids are discussed in detail under the following heads:

(a) Phenol.

(b) The cresols, xylenols, and cresylic acid.

(c) Synthetic tar acids other than phenol.

PHENOL

Description and uses.

Phenol (commonly called carbolic acid) is a tar acid obtained from two sources: (a) From one of the fractions recovered in the distillation of coal tar, a byproduct resulting from the manufacture of coke in byproduct ovens, and from the manufacture of coal gas; (b) from benzol, by synthesis. The second source has been the more important since 1923. Phenol, when pure, is a colorless substance of interlaced or separate needle-shaped crystals with a characteristic aromatic odor. It is corrosive to the skin and to mucous membrane. When pure it is water white, melts at about 42° C., and boils at about 181.5° C. It was discovered in 1834 by Runge.

Phenol is used today chiefly as a component of tar-acid resins. It is also widely used as an antiseptic and disinfectant, in the manufacture of explosives (picric acid and ammonium picrate), and as an intermediate for certain dyes and medicinals. Salicylic acid and its derivatives—aspirin, salol, and methyl salicylate (artificial oil of wintergreen)—are important medicinals made from phenol. Another use is in the extraction of lubricating oils. The relative importance of these various uses in recent years is indicated by table [58], which gives the estimated domestic consumption of phenol by uses in 1936-37.