II.--THE ATROPINE OF DATURA STRAMONIUM.
Planta has already tried to show that atropine is identical with the daturine obtained by Geiger and Hesse, founding his opinion on facts which we nowadays look upon as doubtful. This identity was generally admitted by all chemists. The pharmacologists, headed by Soubeiran, Erhardt, Schroff, and Poehl, were much more reserved in their judgment. I thought it as well, therefore, to recommence the study of daturine, the more so as I had already determined the incorrectness of the long accepted point of fusion of atropine, and that my researches on hyoscyamine convinced me that this base is an isomer of atropine, although very analogous to it. I have also shown that Merck's daturine differs from atropine, and is merely pure hyoscyamine. A short time afterward there appeared a paper by Schmidt which again asserted the identity of daturine and atropine. I therefore requested Mr. Merck, of Darmstadt, to send me all the bases which he obtained from datura. This eminent manufacturer was good enough to comply with my request, and sent me two products, one of which was marked "light daturine," the other "heavy daturine," the separation of which was effected in the following manner: The solution of crude daturine in concentrated alcohol was mixed with a little hot water; this treatment caused the deposition of the "heavy daturine," while the "light daturine" remained in the mother liquor. The "heavy daturine," of which only a small quantity is obtainable, is far from being a body of definite composition, that is to say, it is a mixture of atropine and hyoscyamine. If we convert the base into a double gold salt we obtain by a single crystallization a dull looking salt, melting at from 275° F. to 280° F., the appearance of which is very different to that of atropine. I have succeeded in splitting up "heavy daturine" by two different methods. By recrystallizing the gold salt six times from boiling water, the salt of hyoscyamine, which melts at from 316° F. to 323° F., crystallizes our first, and by the successive evaporation of the mother liquor at last obtain the pure gold salt of atropine, which melts at 275° F. to 280° F. If we only want to isolate the atropine, it is better to crystallize the free base two or three times from alcohol at 50 per cent., always taking the earliest formed crystals.
These facts prove the presence of atropine in datura; but while Planta and Schmidt assert that only this alkaloid is found in the plant, I have proved that the proportion of atropine in it is but small, while its richness in hyoscyamine is great. I think, therefore, that both Planta and Schmidt must have worked with a mixture of atropine and hyoscyamine. It is true that Schmidt had received pure atropine under the name of daturine, for I have proved most conclusively that the so-called daturine supplied by Trommsdorff, of Erfurt, is pure atropine and nothing else. It has no action whatever on polarized light.