CARBOLIC ACID. (Fa., Acide carbolique ; GER., Carbolsaurc.) SYNONYMS : Plienie Acid; Phenol; Phenylic Hydrate ; Phenylic Alcohol ; Coal Tar Cressoto. Formula: O,11„0 = Pure carbolic acid is a colourless crystalline solid, which melts at 42.21' (108° F.) to a colour less, limpid liquid slightly heavier than water. Carbolic acid boils when pure at 182^ and dietils without decomposition. The crystals readily absorb moisture from the air, whereby their fining point is lowered, owing to the formation of a hydrate of the compuoition, C611,30,H20, con taining 16.07 per cent. of water, and melting at 17.2° (63° F.). In very moist air this hydrate absorbs still more water, and the product remains fluid at a still lower temperature. When water is gradually added to absolute carbolic acid as long as it continues to be dissolved, the resultant liquid contains about 27 per cent. of water (by weight), and thus approximates closely to the composition Cal180,2Hz0, which requires 27.7 per cent. of water. If the liquid so obtained be really a compound, it is ono 'of the weakest nature, for by agitating it with four volumes of benzene the carbolic aoid is dissolved, and the water wholly separated. The liquid hydrous carbolic acid obtained as above is readily frozen by the cold resulting from the mixture of strong hydrochloric acid and crystallized sulphate of sodium.
Liquid hydrous carbolic acid dissolves in about 11.1 times its measure of culd water. This corresponds to a solubility of 1 part by weight in 10.7 for the absolute acid, the saturated solution containing 8.56 por cent. of real phenol. Although aqueous solutions of carbolic acid do not redden Minus paper, in weak alkaline solutions carbolic acid is much more eatable than in pure water. With equivalent amounts of the strong bases it forms definite compounds. The potas sium and sodium salts are readily soluble in water, and are not decomposed on dilution.
Carbolic acid is miscible in all proportions with alcohol, glacial acetic acid, and glycerin.
Absolute oarbolic acid is miscible in all proportions with ether, benzene, carbon disulphide, and chloroform. When aqueous carbolio acid is shaken with an excess of either of these solvents, tho phenol dissolves, and the contained water separates.
In cold petroleum ephit carbolic acid is but slightly soluble. It may be obtained in fine crys tallhie needles by suddenly cooling the liquid by a freezing mixture.
The taste of carbolic acid is biting, and at the same time sweet. The odour is usually strong and characteristic, but both smell and taste are much less marked in very pure specimens than in the crude article.
Commercial carbolic acid often turns red in the light; the cause is uncertain.
Strong carbolic acid dissolves dry gelatin completely, but gelatin coag-ulates when carbolic acid is added to its aqueous solution.
Phenol coagulates albumin, if3 a powerful antiseptic, nets as a caustic on the skin, and is powerfully poisonous. When taken internally in a concentrated condition, it destroys life very quickly. Numerous instances of poisoning are on record in which carbolic acid has been taken or administered in mistake for medicine.
When applied externally, carbolic acid appears to act on the system by paralyzing the nerve centres. It is a curious fact that even momentary contnet of the strong acid with any considerable surilice of the lower part of the body is usually fatal. Thus, a child who used a privy on the seat of which carbolic acid had been spilt, eo that the liquid came in contact with his buttocks, died as a consequence. The foreman of a carbolic acid works stepped into a vessel of carbolic scid which wetted him up to the knees. Ile immediately jumped into water and took other precautions, but died the noxt day. On the other hand, carbolic acid has often been applied to the arms and upper