QUINOLINE, CHINOLIN, LEUCO LINE, C,H,N. Runge (1834) isolated at a high boiling point an oily basic substance from coal tar to which he gave the name geukol.D Gerhardt (1842) obtained an oil by distilling quinine or cinchonine with caustic potash. He called it quinolein from its relation to quinine, but later the name was changed by Wolaler to quinoline. Hofmann (1843) showed that leukol and quinoline were identical. It occurs also in bone-oil and the tar from brown coal, strych nine and other plant alkaloids give it with caus tic potash. As usually made in quantity by the interaction of 60 parts glycerine, 50 parts sul phuric acid and 19 parts aniline, which mixture, after heating, is added slowly to 12 parts of nitro-benzine and the whole boiled for about two hours, or until the reaction is complete. The nitro-benzine remaining unchanged is re moved by blowing a current of air through the mixture, and this is made alkaline by adding caustic soda. It is then distilled with steam which carries over crude quinoline with some admixture of aniline. The latter is removed by
fractionation and the quinoline is further puri fied by oxidation with the dichromates. Quin oline, when pure, is an oily liquid, with a spe cific gravity of 1.095 and a boiling point of 460° F.; at first colorless, but becoming dark on ex posure to the air; possesses a penetrating, dis agreeable odor; is slightly soluble in water and has strong antiseptic properties. It absorbs moisture from the air readily, forming the hydrate. It is a basic substance, forming solu ble and easily crystallizable salts with acids. It is used to some extent in medicine and the arts as an antiseptic, its action being to prevent putrefactive fermentation but not to interfere with alcoholic fermentation. It is used as a throat wash in diphtheria, but has not displaced iodoform in surgical dressings. It gives rise to many compounds used in the manufacture of dyestuffs.