ALKALOIDS. 331 



2. The above solution is not colored by nitric acid (difference 

 from morphine), and not at once by potassium dichromate 

 (difference from strychnine). Prolonged contact with potassium 

 dichromate causes the solution to turn green. 



3. The green solution obtained by the action of potassium 

 dichromate upon atropine which has been dissolved in sulphuric 

 acid, evolves, on the addition of a few drops of water and warm- 

 ing, a pleasant odor reminding of roses and orange flowers. 



4. Solutions of atropine dilate the pupil of the eye to a 

 marked extent. 



Veratrine, Veratrina, C 32 H 50 N0 9 ? An alkaloid, or a mixture of 

 alkaloids, obtained from veratrum officinale. It is a white, 

 amorphous, rarely crystalline powder, highly irritating to the 

 nostrils; nearly insoluble in water, readily soluble in alcohol. 



Analytical reactions : 



1. Concentrated sulphuric acid causes with veratrine first a 

 yellow, then reddish-yellow, intense scarlet, and finally violet- 

 red color. 



2. Veratrine when heated with concentrated hydrochloric 

 acid, dissolves with a blood-red color. 



3. Bromine water colors veratrine violet. 



4. Veratrine forms with nitric acid a yellow solution. 



Caffeine, Caffeina, C 8 H 10 N 4 2 .H 2 = 212 (Theine). Occurs in 

 coffee, tea, Paraguay tea, and a few other plants. It forms 

 long, silky needles, which are soluble in 75 parts of water and 

 in 35 parts of alcohol ; it has a slightly bitter taste and a neutral 

 reaction. 



Caffeine is dissolved by sulphuric acid without color ; when 

 treated with strong nitric acid it forms a yellow liquid which, 

 after evaporation, assumes a purplish color when moistened 

 with water of ammonia. 



QUESTIONS. 



461. What are the three chief forms in which nitrogen enters into 

 organic compounds? 



462. What are amines and amides? 



463. State the composition of aniline, how it is obtained from ben- 

 zene, and by what processes it is converted into aniline colors. 



