XANTHINE. 191 



2. From Urine. Precipitate with baryta water, 

 filter, evaporate to a syrup, and set aside to crystallise. 

 Eemove the crystals, dilute the mother liquid, and boil 

 with cupric acetate. Wash the precipitate thereby 

 produced, dissolve in warm nitric acid, reprecipitate 

 with silver nitrate, wash the precipitate, and crystallise 

 it from dilute nitric acid. Wash the crystals with 

 ammoniacal silver solution, decompose by sulphuretted 

 hydrogen, filter, evaporate to a low bulk, and wash 

 with a little water the deposit of xanthwe. 



3. From Flesh, fyc. Extract the pounded substance 

 successively with warm alcohol and water, evaporate 

 the mixed extracts and filter, precipitate the filtrate 

 with neutral and basic lead and with mercuric acetate. 

 Treat the precipitates by the two latter with hydro- 

 thion in water, filter, and evaporate. Sarkine and 

 xanthine will be deposited; separate by crystallising 

 from hydrochloric acid; the first crystals will be 

 xanthine hydrochlorate, while the mother liquid will 

 contain sarltine (q.v.). Dissolve the former in caustic 

 potash, pass carbonic acid in excess through the solu- 

 tion, and wash the precipitate of xanthine. 



4. Xanthine is almost insoluble in water, in- 

 soluble in alcohol and ether. From hot water it 

 separates in white flocks. An aqueous solution rapidly 

 decomposes. It is nearly insoluble in hydrochloric 

 acid. 



5. Heat a little dry xanthine in a tube ; it will 

 evolve ammonium carbonate and cyanide, and a fetid 

 oil. 



6. Dissolve xanthine in hot ammonia; on cooling 



