It is probable that a crystallization of salts (especially with a base of a high equivalent) would effect this purpose, for in crystallization, other compounds and impurities are concentrated in the mother liquids, while in fractional precipitation, in the present case, an infinite subdivision seems to take place, requiring many steps to accomplish a sufficient purification; and brilliant as Heintz’s results are, considerable labour was required to arrive at them. Heintz’s process of partial precipitation was founded upon the method of fractional distillation, proposed by Liebig for the separation of the lower members of the series of fatty acids; in the latter case presence of an alkaline carbonate, in quantity insufficient to saturate the mixed acids, alters their volatility, while in the former, presence of a salt in insufficient quantity for perfect decomposition changes the relations of _solubility_ of the salt formed, and it does not necessarily follow that the chemical affinity, active in both cases, will afford as _expeditious_ a method in cases of solubility as in those of volatility. FOOTNOTES: [1] Liebig thinks this probable. Ch. Briefe. [2] The degrees of thermometer in this article are centigrade, and the weights grammes. [3] Lehmann, Lehrbuch. [4] Lehrbuch, III. p. 187. [5] Lehmann. [6] The liquid from No. 3 was all absorbed by the pressing cloths, and not collected. [7] Since the above was written, I have received the Journal für Pract. Chemic., Heft III. Band LXIII. in which some late results by Heintz on this point are communicated. He artificially prepared chemically pure stearine from the acid and glycerine, by Berthelot’s process, and found that it had two melting points, first at 55°, then solidifying and melting again when the heat reached 71.6°. [8] Ann. de Ch. & de Ph., xvii. p. 390. [9] See Kolliker, Mic. Anat., II. 1st Part, page 16.