The conclusiveness of this process depends upon the fact, that absolute alcohol cannot dissolve from solid organic substances such a proportion of lactate, tartrate, acetate, sulphate, or phosphate of potash, or chloride of potassium, as to be acted on by chloride of platinum or perchloric acid.[430]—It is to be observed that carbonate of potash singly is insoluble in absolute alcohol; but it becomes soluble in that fluid, when it is conjoined with various organic matters. Hence it is that this process, intended fundamentally for caustic potash alone, is applicable to carbonate of potash also. _Process for Soda and its Carbonate in Organic Mixtures._—These substances may be separated by the method just described for potash. If the alcoholic solution of the extract of the suspected matter be alkaline in its action on litmus, and be afterwards found to contain soda or its carbonate, the evidence of these substances having been derived from without is satisfactory, because the carbonate of soda contained in many animal matters cannot be so detached. But if no indications of the presence of soda be thus obtained, it is not enough that soda be found in the alcoholic solution of the incinerated alcoholic extract, because the natural carbonate of soda of animal matter may be separated in that manner.[431] SECTION II.—_Of the Action of the fixed Alkalis, and the Symptoms they cause in Man._ The action of the two fixed alkalis and their carbonates on the animal system is so nearly the same, that the facts which have been ascertained in respect to one of them will apply to all the rest. The operation of potass and its carbonate has been carefully investigated by Professor Orfila,[432] and by M. Bretonneau of Tours.[433]