Acidum Salicylicum

Salicylic Acid

Salicylic acid. Acide salicylique, Fr.; Sali-cylsaure, Ger. An organic acid, existing naturally in combination in various plants, but most largely prepared synthetically from carbolic acid.

Properties

Salicylic acid crystallizes in needle-shaped crystals, which are soluble in alcohol and ether, and in hot but not in cold water. It is without smell, and its taste is slight and not disagreeable. The solubility of salicylic acid in cold water is increased by the presence of neutral salts. Three parts of phosphate of sodium will render one part of the acid easily soluble in fifty parts of water. Borate of sodium is still more efficient in promoting the solubility of the acid, and, as boracic acid has properties corresponding to salicylic, the borate should be preferred for this purpose. It has been shown that ten parts of salicylic acid can be dissolved in one hundred parts of water by the addition of eight parts of borax (Bose). The borax should be first dissolved by the aid of heat, and the salicylic acid should be added gradually to the hot solution of borax. On cooling, filtration is necessary to separate a small quantity of undissolved residue.

The dose of salicylic acid for internal administration ranges from ten grains to one drachm.