Source and Composition. Naphtalin, C10H8, is a hydrocarbon product formed during the manufacture of ordinary coal gas. Chemically, it is one of the benzene derivatives, being formed by the union of two benzene groups in an overlapping ring. (See ante, page 180.) When redistilled it crystallizes in colorless, rhombic plates, of tarry odor, and burning, aromatic taste, insoluble in water, dilute acids or alkalies, and but sparingly so in alcohol.

The Dose of Naphtalin is from gr. ij-viij, up to gr. lxxx per diem for adults;—and for children gr. j-iij, every three hours. Being quite insoluble in water it must be given in emulsion, or as a powder with sugar in wafers or capsules. It is best flavored with oil of bergamot.

Derivatives. From Naphtalin we have—

Naphtol, Beta- or Iso-naphtol, C10H7OH,—one of several kinds of Naphtol: is sparingly soluble even in hot water, but is soluble in alcohol, ether, chloroform, olive oil and vaseline. Used as ointment, 1 to 5 for adults, but for children not over 2 per cent.
*Hydronaphtol, C16H7OH,—glistening, micaceous scales, sparingly soluble in water, freely soluble in alcohol, oils, etc. Used as an antiseptic, and in ointment or powder locally, diluted with oxide of zinc, 1 to 50.

Physiological Action. Naphtalin is destructive to all forms of low life, and hence is antiseptic in a high degree, but must be intimately mixed with the substances upon which it is to act. Internally it is a stimulant expectorant of decided power, and disinfects the contents of the intestinal canal. Being so sparingly soluble, but little of it is absorbed, and hence it does no injury to the organism. What is taken up by the blood is excreted by the urine, partly unchanged, partly as naphtol and perhaps some as phenol. Naphtol is more easily absorbed, and causes vomiting, hematuria, convulsions, and unconsciousness. Hydronaphtol is a powerful and non-irritating antiseptic, nonpoisonous, non-corrosive, freely soluble in alcohol, glycerin, fixed oils, etc., in cold water, 1 to 2000; and in hot water 1 to 100, precipitating as the water cools, but leaving a saturated solution of 1 to 1000, which is perfectly inhibitive of the germs of putrefaction in all putrescible fluids (Levis). The claims made for it are that it is 12 times as effective as carbolic acid, 30 times as potent as salicylic acid, 60 times as efficient as boric acid, 600 times as antiseptic as alcohol, and that it is entitled, as a true antiseptic, to stand next to mercuric chloride in the comparative tables (Levis).

Therapeutics. Naphtalin is employed as an antiseptic for the intestinal canal in typhoid fever, diarrhoea, both acute and chronic, tubercular diarrhoea, etc. It renders the urine aseptic and may be employed in vesical catarrh. It is also used internally for humoral asthma, verminous affections, and the chronic pulmonary catarrh of the aged. Locally, it has high value as an antiseptic, for indolent ulcers, sloughing wounds, open cancers, pus cavities, etc. Painted over organic remains it effectually prevents the ravages of insects. Naphtol is employed like tar for a therapeutic action upon the skin, in hyperidrosis, scabies, eczema and local sweating, in ½ to 5 per cent. alcoholic solution, or as a 10 per cent, ointment. Hydronaphtol is also highly esteemed for antiseptic purposes generally, by those who have used it, and is of benefit as an external application in many skin diseases. Its non-toxic and non-irritant qualities render it the most useful and most generally available of the three.

A Compend of Materia Medica, Therapeutics, and Prescription Writing, 1902, by Sam'l O. L. Potter, M.D., M.R.C.P.L.