PHENIC, OR CARBOLIC, ACID AND DERIVATIVES.
Phenic or phenylic acid, carbolic acid (acidum carbolicum, U. S. P.), phenol, phenyl-hydrate, phenylic alcohol, or coal tar creasote obtained by fractional distil lation, at 338° to 446° F. Pure carbolic acid (acidum carbolicum, U. S. P.) oc curs in long, colorless needles, melting at 05° F. and having a characteristic odor and, when highly diluted, a sweetish taste. Carbolic acid deliquesces in moist air and becomes red on exposure to the light. It is freely soluble in alcohol, ether, chloroform, and glycerin, and slightly soluble in water. The pharma copoeia recognizes a crude acid (acid urn carbolicum crudum, U. S. P.), which is a mixture chiefly of cresol and phenol and occurs as a dark, oily liquid, having a strong tar odor, and is partly soluble in water. This crude acid is used chiefly for disinfecting purposes either in solu tion (1 in 50 to 200) or mixed with chloride of lime, slaked lime, etc.; the crude acid is not adapted for wounds. Between these official preparations there are others of various grades of purity. Five grades, known by numbers, are made. The pure acid in colorless crys tals is known as number one, and is alone fit for internal use. Number two is also crystalline. Numbers three, four, and five are impure, containing other in gredients of coal-tar, especially cresol.
The crystals of pure carbolic acid may be liquefied by the addition of 5 per cent. of water, a clear solution resulting; the further addition of water produces turbidity until the proportions are re versed (1 to 20), when it becomes per manently clear and remains unaffected by further dilution.
Preparations and Doses.—Acidum car bolicum, U. S. P. (pure crystals), 1 to 3 grains.
Acidum carbolicum crudum, U. S. P. (impure, 90 per cent.), for disinfection.
Glyceritum acidi carbolici, U. S. P. (glycerite, 20 per cent.), 2 to 5 minims.
Unguentum acidi carbolici, U. S. P. (ointment, 5 per cent. carbolic acid).
Physiological Action.— Locally, car
bolic acid is an energetic caustic, in di lute solution an irritant. In concen trated form, when brought in contact with the tissues, it causes rapid disor ganization of the part and the formation of a hard mass, which does not disappear for some time. If one of the extremities be immersed in a comparatively weak solution of the drug, a contraction of the capillaries and consequent pallor of the skin results, with a certain amount of local anesthesia — a stronger solution producing some preliminary burning. Upon the mucous membrane the acid causes, first, a sensation of burning pain, then amusthesia, leaving a white eschar (Pouch et).
When administered internally in toxic doses it gives rise to convulsions of spinal origin, to which are added at first in creased reflex activity. This being fol lowed by paralysis, it is evident the spinal centres are first stimulated, then depressed. The nerves and muscles, as shown by Salkowski and Hoppe-Seyler, are not distinctly paralyzed however, since they respond actively to galvanic stimulation (Wood). The arterial press ure is reduced and the heart depressed. Gies has shown that carbolic acid para lyzes the vasomotor centre in the me dulla before affecting the heart. The condition of the blood induced in ani mals is one of oligocytluemia rather than oligochromminia, as the reduction of blood-corpuscles is not accompanied by any alteration in the percentage of hmmoglobin (W. J. Wilkinson). Respi ration is at first greatly increased in fre quency, owing, mainly, to a stimulat ing influence exerted upon the respira tory centres during the first stages and in part to stimulation of the peripheral vagi (Salkowski). As to the effects on temperature, H. C. Wood concludes from the experiments of H. A. Hare and E. Erls that carbolic acid may affect the thermo genie functions in two ways: first, by di minishing the production of heat; second, by increasing the dissipation of heat.