DR THOMAS R. FRASER ON STROPHANTHUS HISPIDUS. 1005 



beautiful crystallisation of strophanthidin may be observed in the solution. The crystals 

 have for the most part the appearance represented in Plate VII. fig. 10, but in portions of 

 the field, where only a thin layer of fluid is interposed between the cover-glass and the 

 slide, their form is modified to that of groups of long and slender radiating needles, and 

 of fan-shaped crystalline plates. 



A well-defined crystallisation produced in such circumstances in a solution of a phar- 

 macologically active substance, is of so rare occurrence that it may usefully be applied as 

 a test for strophanthus extract. It would probably, also, be an easy matter to devise a 

 quantitative test for all strophanthus preparations, depending on the amount of crystal- 

 line strophanthidin produced in this reaction. 



If a watery solution of the extract be acidified, and, after a short time, shaken with 

 chloroform or amyl alcohol, the separated chloroform or amyl alcohol yields on evapora- 

 tion a crystalline substance. It is, accordingly, an easy matter to obtain a well-defined 

 crystalline product from the extract; but it will, at the same time, be found that the 

 original solution now contains glucose, and the crystalline substance thus obtained is not 

 therefore strophanthin, but strophanthidin, one of the products of its decomposition. 



Notwithstanding the circumstance that dilute acids so readily decompose the gluco- 

 side present in the extract, this decomposition does not appear to occur spontaneously in 

 a watery solution of the extract, although its reaction is decidedly acid. In such a solu- 

 tion, a fungous growth makes its appearance in a short time ; but even in a solution made 

 more than two months previously and containing an abundant fungous growth, no glucose 

 could be detected by Fehling's reagent. At this time, also, the solution appears to be as 

 intensely bitter as when it was first prepared. When, however, the naturally acid solution 

 of the extract in water is boiled for a short time, a small quantity of glucose is produced ; 

 but the decomposition is so slight that no formation of crystalline strophanthidin can be 

 observed. (See Table X. Analysis No. 15.) 



On the other hand, the glucoside in the extract is quickly and completely decom- 

 posed by the addition of many acids ; and weak solutions of several acids may, even 

 at the ordinary temperature, produce this decomposition sufficiently to cause crystalline 

 strophanthidin to appear in the solution. 



The following experiment illustrates the action in the cold of a weak solution of 

 sulphuric acid : — 



A 5 per cent, solution of extract in water was acidulated with sulphuric acid so as to 

 produce a 0"4 per cent, solution of acid. The solution very soon became slightly turbid; 

 in two days, the turbidity had greatly increased; in four days, a few small crystalline 

 rosettes had appeared at the bottom of the solution, which was now less turbid ; and in 

 five days, there was a considerable pale brownish-yellow incrustation at the bottom and 

 sides of the vessel, consisting chiefly of round groups of lancet-shaped crystals, while the 

 fluid was now only faintly turbid, and much less coloured. The crystals, which could 

 not be removed from the vessel without some loss, when washed and dried, weighed 18*3 

 per cent, of the extract used. The filtered solution, after having been neutralised, was 



