40 TECHNICAL DRUG STUDIES. 



distinctive reactions of gelsemium and to the appearance of the pre- 

 cipitates under the microscope. These facts are of importance because 

 combinations of belladonna and nux vomica and of gelsemium and 

 nux vomica are on the market. 



The purple test given by the opium alkaloids could hardly be 

 mistaken for that given by strychnin, as the color is very lasting in the 

 former case. Some of the free alkaloids obtained from opium were 

 treated with sulphuric acid and bichromate, and it was found that 

 narcein and papaverin gave a purple color, while no similar reaction 

 was obtained with thebain, narcotin, codein, or morphin. 



