Codein has been employed since its discovery in 1832 for various affections accompanied by pain, as a substitute for morphin, which had been in use for seventeen years before the above date. The drug has gained a prominence not hitherto accorded it, with the appearanceof epidemic influenza and its sequelæ throughout this country during the severe winter just past.
Codein is administered alone or as one of its salts. It forms combinations with the mineral and organic acids, which are much more soluble than the alkaloid itself. The acetate, citrate, hydrobromate, hydrochlorate, hydroiodate, nitrate and sulphate have physical and therapeutic properties in common and are soluble in from five to twenty parts of cold water, more so in hot water, from which they recrystallize to a certain extent on cooling. The phosphate is a white crystalline powder, soluble in four parts of cold water, and is especially suited for hypodermic