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.
Dr. Guy’s “subliming cell” is a ring of glass tubing about ⅛-inch long and ⅓ to ½-inch diameter, ground true and smooth at top and bottom, resting on a circle of thin microscope glass, and covered with another similar circle. The alkaloid, thoroughly dry, is placed on the lower disc (a drop of the solution may be evaporated on it), the whole fitted together, and floated on mercury, or better, fusible metal, contained in a small glass beaker nearly full, supported on wire gauze over a small flame. A thermometer held by a clamp dips in the liquid metal. With a hand lens of as high power as possible, the melting point, and also the point when the first sublimate occurs on the upper glass, may be observed. As soon as the sublimate has become sufficiently distinct, the upper disc is removed, replaced by another, and examined under ¼-inch power of the microscope. The heat is slowly raised till charring occurs, and anything characteristic noted.
Morphia gives a clouding, consisting of minute dots, at 150° C.; from 188° to 200° C., distinct crystals are obtained; then it commences to brown, melt, and carbonize.
Strychnia gives a minute sublimate of fine needles at 169° C., and melts at about 221° C.
Brucia melts at 151° C., browns easily, but gives no true sublimate.