448 THEOBBROMINE. 



C 20 H 21 ^T0 4 , which crystallizes from alcohol in small, 

 colorless, granular crystals of a diamond lustre, or long, 

 flat needles, and is reconverted into berberine by nitric 

 acid. 



2. Oxyacanthine. White amorphous powder ; be- 

 comes yellow in direct sunlight. Crystallizes from 

 alcohol and ether in fine colorless prisms. Insoluble in 

 water, soluble in alcohol and ether, particularly in the 

 boiling liquid. 



9. Theobromine. 

 C 7 H 8 N 4 2 . 



Occurrence. In the cacao-bean. 



Preparation. The watery extract of the broken-up 

 beans is precipitated by lead acetate ; filtered ; the lead 

 removed from the nitrate by sulphuretted hydrogen ; 

 then evaporated; and the base extracted from the resi- 

 due with absolute alcohol. 



Properties. White crystalline powder of a weak, bit- 

 ter taste; but slightly soluble in water, alcohol, and 

 ether, more easily in ammonia; sublimable. Weak 

 base. 



The hydrochlorate, C 7 H 8 N 4 2 .HC1, crystallizes from a 

 solution in hydrochloric acid. 



The solution of the free base in ammonia gives a 

 granular crystalline precipitate of theobromine-silver, 

 C 7 H 7 AgN 4 2 , when boiled for a length of time with 

 silver nitrate. 



10. Caffeine, The'ine (Methyl- Theobromine). 

 4 2 + H 2 0. 



Occurrence. Contained in coffee, tea, Paraguay tea (of 

 Ilex Paraguayensis), in cola-beans and in guarana (a 

 mass prepared from the fruit of Paullinia sorbilis) ; and 

 is obtained from them by the same method as that 

 described for theobromine. ' 



Formation. By heating theobromine-silver with 

 methyl-iodide in sealed tubes for twenty-four hours. 



Properties. Colorless, long and very thin prisms of 

 a silky lustre ; of a weakly bitter taste ; difficultly solu- 

 ble in cold water and alcohol, more easily in hot water. 



