By the term phenoresorcin is meant, by River-din, a mixture of carbolic acid and resorcin: sixty-seven parts of the former and thirty-three parts of the latter. This mixture crystallizes by cooling, and on the addition of ten per cent of water becomes a liquid which mixes with water in all proportions. Combining thus the virtues of both remedies, phenoresorcin offers many advantages, and may well repay more elaborate investigations.

Hydroquinon and Pyrocatechin; Kairine and Kairoline; Chino-line.—In the search for an artificial quinine, produced by a synthetical process, various substances, more or less closely related, have been formed. Of these, hydroquinone and pyrocatechine are very similar in all respects to resorcin. They correspond in physiological actions, and have the same power to depress febrile temperature. They are also closely allied to quinine chemically, and possess distinct antiperi-odic power. When first produced, they were proposed as substitutes for quinine; the close chemical relationship was supposed to imply an equally close physiological affinity. Further studies have shown that, while these agents are very useful, they are inferior in all respects to quinine. Hydroquinon and pyrocatechin are very closely allied to resorcin.

The actions of kairin, hydroquinon, etc., have not proved satisfactory, and so much depression has been caused by them as to be dangerous. The more recent and manageable remedies, considered further on, have now displaced them entirely.

Kairin is a powder having a pale buff color, is slightly soluble in water, and has a bitter, somewhat aromatic, and, to most persons, a very disagreeable taste. If inclosed in a wafer, which is the most agreeable mode of administering it, a quantity of water should be taken after it, to prevent the caustic action on the mucous membrane.

Kairolin is, chemically, methyl-hydride of chinolin. It is very much less active than kairin, but the effects when produced are more lasting. The dose of kairin, as an antipyretic, is from fifteen to thirty grains, given in anticipation of the febrile rise, or it may be administered in smaller doses at intervals—for example, five grains every hour, until the desired impression is effected. Kairolin, being less active by half, must be given in corresponding quantity.