2 PROFESSOR FRASER AND DR DOBBIN ON 



from strophanthin, and 30°/ o from the extract, although more frequently the extract 

 yielded from 20 to 25°/ o . 



In order to effect the complete decoloration of the crystals, from whatever source they 

 have been obtained, they may be washed with distilled water and digested for a few 

 hours with a little pure charcoal in a hot rectified spirit solution. The filtered hot solu- 

 tion deposits, on cooling, colourless crystals of considerable size, which continue to form 

 on the spontaneous evaporation of the solution. The crystals consist of four-sided, 

 apparently monoclinic, prisms, terminated either by the end faces alone, or also by 

 pyramidal faces. To ensure the absolute purity of the product, it may several times be 

 recrystallised from alcohol, or precipitated by petroleum ether or by water from a con- 

 centrated solution in alcohol, or in several of the other solvents afterwards to be mentioned. 



General Characters. — The crystals are easily broken down in a mortar, but the 

 particles are somewhat adhesive, and may even form a friable paste during triturition. 

 A solution in water is neutral in reaction, and a moderately persistent froth is produced 

 when it is shaken. A saturated watery solution is strongly, though not intensely, bitter ; 

 and slight bitterness can be perceived also in a solution of one part in sixty thousand. 



Solubilities. — Unlike strophanthin, strophanthidin is insoluble in glycerine, very 

 slightly soluble in cold water, only moderately soluble in rectified spirit, and more soluble 

 in absolute than in dilute alcohol. Absolute alcohol and acetone, however, dissolve a 

 larger quantity of it than of strophanthin. It resembles strophanthin in being insoluble 

 in olive oil. 



The results of determinations of its solubility in various, liquids, at the ordinary 

 temperature, are as follows : — 



Absolute ethyl alcohol (sp. gr. 796) 



1 in 



30, or 3 "3 per c 



Acetone ..... 



)5 



35, or 2-85 



Rectified spirit (sp. gr. *838) . 



59 



47, or 2-1 



Amyl alcohol (sp. gr. *820) 



5) 



165, or 0-606 



Chloroform (sp. gr. 1*497) 



)! 



690, or 0-1449 



Distilled water .... 



)5 



2150, or 0-0465 



Ethyl ether (sp. gr. 723) 



5) 



2196, or 0-0455 



Ethyl ether (sp. gr. 730) 



)J 



2222, or 0-045 



Petroleum ether (boiling below 50° C.) 



Absolutely insoluble. 



Its solubility in several of these liquids, as for example in rectified spirit, is much 

 increased by elevating the temperature. After hot saturated solutions in alcohol have 

 become cool, and have ceased to deposit strophanthidin, they hold in solution a larger 

 quantity than alcohol is capable of dissolving without the aid of heat. 



Strophanthidin is precipitated by petroleum ether from solution in absolute alcohol, 

 acetone, rectified spirit, amyl alcohol, ethyl ether, and chloroform ; and by water from 

 solution in absolute alcohol and rectified spirit. Precipitation is, however, only slowly 

 produced in rectified spirit and ethyl ether solutions. The precipitates, either imme- 



