PROFESSOR FRASER AND DR DOBBIN ON 



Reactions of Dry Strophanthidin. 



1. When strong sulphuric acid was placed in contact with a little finely powdered 

 strophanthidin, an immediate orange red colour was produced, and slowly a bluish-green 

 colour appeared at the margins. In 40 minutes the green colour had extended itself, 

 and soon afterwards it had entirely displaced the red. The green, in its turn, slowly faded, 

 and the whole then assumed a faint brownish-yellow tint, which persisted for several 

 hours. After the addition of strong sulphuric acid had developed an orange-red colour, 

 the subsequent addition of nitric acid immediately changed the colour to dusky yellow, 

 which slowly faded to pale brownish-yellow. 



When strophanthidin, moistened with strong sulphuric acid, was slowly heated 

 between 42° and 45° C, the orange-red first produced became a yellowish-red with a 

 slight green tint at the margins, then altogether greenish-yellow, and finally brown. 



2. Contact in the cold with dilute sulphuric acid (10 per cent.) failed to develop any 

 colour within half an hour. On now heating gradually to 48° C, yellowish-green 

 appeared at the margins and yellow at the centre ; the green soon became very dark 

 until it was almost black, and the yellow at the centre changed to brown ; and in about 

 an hour and a half the whole assumed a brownish-black colour. 



3. Strong nitric acid produced in the cold merely a very faint brown tint, which 

 appeared only after prolonged contact, but remained unchanged for several hours. On 

 the addition of strong sulphuric acid, the very faint brown tint immediately became 

 pinkish-yellow, which very soon changed to greenish-yellow. 



When strophanthidin was mixed with strong nitric acid, and placed in an air chamber 

 with a temperature of 43° C, which was gradually raised to 52°, in one minute a faint 

 pink tint appeared, which very soon changed to brownish-yellow, and in a few minutes to 

 pale yellow, which slowly deepened in hue until a deep yellow, almost gamboge, was 

 developed. The last colour remained for more than an hour and a half. 



4. Dilute nitric acid (10 per cent.) produced no change in the cold. When, however, 

 the temperature was slowly raised to 47° and 48° C, a light orange colour was speedily 

 produced, which persisted for several hours. 



5. Contact in the cold with strong hydrochloric acid merely caused the particles of 

 strophanthidin to become slightly brown, even when the contact was continued for 

 several hours. 



On slowly heating to from 43° to 48° C. with strong hydrochloric acid, yellow appeared 

 at the edges and gradually spread over the whole surface of the mixture, and this yellow 

 colour remained for several hours, during which the heating was continued. 



6. Dilute hydrochloric acid (10 per cent.) produced no change in the cold. 



On heating between 47° and 48° C, an orange colour was produced, which persisted 

 for several hours. 



7. Strong sulphuric acid and bichromate of potassium produced a crimson colour, which 



