1 62 



A TEXT-BOOK OF BOTANY. 



ened drug are mounted directly in sulphuric acid, there separate 

 very soon small acicular or rod-shaped crystals of berberine and 

 hydrastine (Fig. 95). This is one of the most satisfactory of 

 microchemical tests of the alkaloids that is known, and Leuff has 

 shown that they can be readily determined even in the endosperm 

 cells in the seeds of hydrastis (Pharm. Post, 1913, p. 977). 



Caffeine is an alkaloid which is rather widely distributed, and 

 its presence can be easily determined, in dried material as 

 coffee seeds, in several ways. ( I ) It may be sublimed, the long, 



\ 



B 



FIG. 95. Alkaloids in Hydrastis: A, prismatic crystals which separate after a time 

 on treatment of sections of the rhizome of hydrastis or its powder with sulphuric acid; B, 

 the separation of needle-shaped crystals of the sulphates of the alkaloids in the paren- 

 chyma cells of hydrastis upon treatment with sulphuric acid. 



silky needles of caffeine being deposited upon a watch crystal 

 or a microscopic slide. (2) Similar crystals may separate from 

 aqueous or hydro-alcoholic mounts of the material. (3) The most 

 satisfactory method for the detection of caffeine is to form a 

 double salt with gold chloride, the crystals of which are very 

 characteristic (Fig. 96). The test may be applied to coffee seeds, 

 cola nuts, tea leaves, guarana, etc., as follows : Sections are placed 

 in strong hydrochloric acid and slightly heated ; then one or two 

 drops of a solution of gold chloride are added and the sections 

 pushed to one side, allowing the liquid to evaporate. Near the 



