It has been proposed to precipitate the original spirituous extract by neutral or basic acetate of lead, which throws down many impurities, but leaves the alkaloids in solution. After filtration, the liquid is treated with a current of sulphuretted hydrogen to remove lead; again filtered, evaporated (as speedily as can be done without overheating) to a moderate bulk, and treated with a little ammonia and with ether-chloroform as before. If the sulphuretted hydrogen be left exposed to the air for some time, it oxidizes to sulphuric acid, which, during and after evaporation, tends to destroy the alkaloid. Hence I have found it advisable to remove the H_{2}S quickly by a current of carbonic acid and warming—previous to evaporation. But this process is not good for alkaloids, as sulphur compounds are often formed, which interfere with subsequent operations. The foregoing process may fail to extract _morphia_, _curarine_, and _solanine_, as these, being very little soluble in ether-chloroform, may remain behind in the aqueous liquid. This, therefore, should be afterwards treated in one of the following ways:— 1. Heat some redistilled amylic alcohol nearly to boiling (it boils at 120° C.), add an equal volume to the aqueous (alkaline) solution; shake vigorously, separate while still hot, and shake again with a fresh, but rather smaller, quantity of the hot solvent. The united amylic alcohol solutions will contain all the morphia, but can only be distilled in vacuo, since at 120° C. the stability of the morphia would be endangered. It is better to extract the morphia from the amylic solution by shaking with successive small portions of weak acetic acid, separating each time, till the acidity remains unneutralized. The alkaloid will now be in the acid solution. Nearly neutralize this with ammonia, evaporate at a gentle heat, and apply the special tests. 2. Instead of the above, the aqueous alkaline solution may be agitated with a mixture of equal volumes of ether and _pure_ acetic ether (the latter having been previously purified from free acid by standing over powdered carbonate of lime). Although this mixture does not extract the morphia so readily as amylic alcohol, it has this advantage that, after separation from the aqueous layer, it can be evaporated at a moderate temperature, when the morphia, if in sufficient quantity, will be left in the crystalline state, and can be tested as usual. If sufficient material be at hand, of course both processes may be used.[5] Selmi (Gazz. Chim. Ital. vi., 32) has given a process for alkaloidal extraction of which I have no experience. When the alkaloid is obtained in a sufficiently pure form and in sufficient quantity, the sublimation process of Dr. Guy, as improved by Blyth, may be used. For the entire original method, see Blyth’s Practical Chemistry, page 285.