SALICYLIC ACID AND ITS SALTS.—The salicylates occur in various plants, but the principal source of the acid for medicinal purposes is carbolic acid, from which it is manufactured. Salicylic acid occurs in fine white crystals, readily soluble in alcohol, much less soluble in water. It is strongly antiseptic, and is an irritant. Taken internally it slightly increases the flow of urine and bile, and exerts a somewhat depressing action on the circulatory system and, in large doses, on the respiratory system. It reduces the temperature slightly in fevers ; and it increases the excretion of nitrogenous substances. The first effects noticed after a large dose are usually a buzzing in the ears and some deafness. There may be headache, dimness of vision, a soft, weak pulse, with temperature below the normal, and, possibly, unconsciousness, paralysis, and convulsions. Nose bleeding, free sweating, and various skin eruptions have been noticed after its use. There is no known antidote for salicylic acid, the treatment consisting in getting rid of it as quickly as possible, and in treating the symptoms as they arise.
In acute rheumatic fever, salicylic acid acts almost like a specific, often controlling the symptoms in a remarkable manner. It is frequently used in lumbago and sciatica, and is recommended in gout. ]n quinsy and in rheumatic headaches it is very useful. Salicylic acid is used externally for its antiseptic and stimulating properties in certain diseases of the skin. Strong solutions are sometimes used as caustics for warts, corns, etc. The salts of salicylic acid are used internally much more frequently than the acid itself, as they are less irritating to the stomach and almbst equally efficacious. There are several of these salts—sodium, potassium, stron tium, etc.—sodium being perhaps the most commonly used. The dose is five to thirty grains. Salicine, aspirine, salophene, and salol all depend largely for their action on the salicylic acid which they contain or generate.