There are two officinal salts of the alkali Lithia; one, the carbonate, recognized by both the U. S. and Br. Pharmacopoeias; the other, the citrate, only by the British. As it is only the former of these that belongs properly to the antacids, I shall treat principally of that, though referring shortly to the citrate and its uses. The scanty supply of this alkali hitherto drawn from natural sources, tends greatly to limit its employment by augmenting the price; otherwise, in consequence of some peculiar and valuable properties belonging to it, there would probably be few alkaline remedies in more extensive use.