404 CONSIDERATION OF CARBON COMPOUNDS. 



Berberine, C, H 17 N0 4 . Found in a number of plants (berberis vulgaris, 

 hydrastis Canadensis, etc.) belonging to entirely different families. It is a 

 yellow, crystalline substance, soluble in 7 parts of alcohol, 18 parts of water, 

 insoluble in ether, chloroform, and benzene. 



Berberine not only forms well-defined, readily crystallizing salts with acids, 

 but it also enters into combination with a number of other substances, as, for 

 instance, with alcohol, ether, chloroform, etc. Some of these compounds crys- 

 tallize well, as for instance, berberine-chlorotorm, C 20 H 17 N0 4 .CHC1 3 . 



Physostigraine, C 15 H 21 N 3 O 2 (Eserine). Found in the seeds of 

 Physostigma venenosum (Calabar bean). The pure alkaloid does not 

 crystallize well, is almost tasteless, and assumes gradually a reddish 

 tint. The sulphate and salicylate are official. Both are white or 

 yellowish-white crystalline powders, which have a bitter taste. The 

 sulphate is readily, the salicylate sparingly soluble in water. 



Analytical reactions: 



1. Five milligrammes of physostigmine dissolved in 2c.c. of 

 ammonia water yield a yellowish-red liquid which, on evaporation 

 on a water-bath, leaves ,a blue or bluish -gray residue, soluble in 

 alcohol, forming a blue solution. Upon supersaturation with acetic 

 acid this becomes violet and exhibits a strong reddish fluorescence. 

 The violet solution leaves on evaporation a residue which is first 

 green and afterward blue. (Plate VII., 7.) 



2. Physostigmine or its salts give with calcium oxide and water a 

 red liquid, which turns green on heating. 



Pilocarpine, C n H 16 N 2 2 . Found in the leaflets of Pilocarpus Selloanus. The 

 alkaloid crystallizes with difficulty ; its solutions in ether, alcohol, or water 

 have an alkaline reaction. The hydrochlorate is official. It is a white, crys- 

 talline powder, which dissolves in fuming nitric acid with a faintly greenish 

 tint. The aqueous solution is precipitated by most of the common reagents for 

 alkaloids. 



Caffeine, Caffeina, C 8 H 10 N 4 O 2 .H 2 O = 212 (Trimethyl-xanthine, 

 Theine, Guaraniri), occurs in coffee, tea, Paraguay tea, and a few 

 other plants. It forms fleecy masses of long, flexible, silky needles, 

 which are soluble in 80 parts of water and in 33 parts of alcohol ; 

 it has a slightly bitter taste and a neutral reaction. 



Caffeine and theobromine show the properties of alkaloids to a 

 much less degree than the majority of the compounds considered in 

 this chapter ; they do not act on red litmus and are but feebly basic. 



Citrated caffeine U. S. P. is obtained by adding caffeine to a solu- 

 tion of citric acid and evaporating the mixture to dry ness. 



Caffeine is dissolved by sulphuric acid without color ; when treated 



