Chemists have long employed the commoner organic acids, especially acetic, oxalic, tartaric, and citric acids in mineral analysis, but with few exceptions they have overlooked the application of these acids to the decomposition of minerals. Acetic acid has been used to separate minerals from their matrix of calcite ; Karsten (Archiv. of Min. XXII, 572) and Sterry Hunt have used it in the proximate analyses of mixtures of calcite, dolomite, and magnesite; calamine and willemite are sometimes distinguished by the gelatinization of the former with the same acid ; Dr. J. Lawrence Smith (Am. J. Sci., [2] XX, 244) has noticed the solubility of anglesite in ammonium citrate ; W. B. snd R. E. Rogers (Am. J. Sci., 1848) have made experiments on the solubility of minerals in water containing carbonic anhydride ; but there is no record of any systematic investigation of the action of organic acids on minerals with a view to the determination of species.