904 



APPENDIX. 



and bases [Figs. 243, 244, ~ 

 cipitate being soluble in a 



245]. It is precipitated by basic acetate of lead, the pre- 

 a solution of the normal acetate. Its preparation from 



[FiG. 245. 



Hypoxanthin-hydrochloride, C 5 H 4 N 4 O.HC1. (Kiihne.)] 

 [FiG. 246. [FiG. 247. 



Xanthin-hydrochloride, C5H 4 N 4 O 2 .HC1. 

 (Kuhne.)] 



Xanthin-nitrate, C 5 H 4 N 4 O 2 .HNO 3 . 

 (Kiihne.)] 



muscle-extract depends on its precipitation first by basic acetate of lead, and then 

 by an ammoniacal solution of silver nitrate after the removal of kreatin. 



Both hypoxanthin and the next body, xanthin, can also be obtained from proteids by the 

 action of putrefactive changes, of water at boiling temperature, of dilute hydrochloric acid (0.2 

 per cent.) at 40 C , and by the action of gastric and pancreatic ferments. 1 Chittenden lias noticed 

 a peculiar difference between fibrin and egg-albumin when submitted to the above processes ; he 

 finds that the latter does not yield hypoxanthin when treated with boiling water, with dilute 

 hydrochloric acid, or gastric ferment, while the former does. Egg-albumin, on the other hand, 

 yields hypoxanthin by the action of pancreatic ferment in alkaline solution, but not so readily as 

 fibrin does. 



Xanthin. C 5 H 4 N 4 2 . 



First discovered in a urinary calculus, and called xanthic oxide. More recently 

 it has been found as a normal, though scanty, constituent of urine, muscles, and 

 several organs, such as the liver, spleen, thymus, etc. 



[FiG. 248. 



Crystals of Xanthin-silver-nitrate, C 5 H 4 N 4 O 2 .AgNO3. (Krukenberg, after Kiihne.)] 



When precipitated by cooling from its hot, saturated, aqueous solution it falls 

 in white flocks, but if the solution be allowed to precipitate slowly it is obtained in 



* Salomon, Zeitschr. f. physiol. Chem., Bd. ii. (1878-1879), S. 60. Krause, Inaug. Diss., Berlin, 

 1878. Chittenden, Journ. of Physiol., vol. ii. (1879), p. 28. See also Drechsel, Ber. d. Deutsch. Chem. 

 Gesell.. Jahrg. xiii. (1880), S. 240. Salomon, Ibid., S. 1160. Kossel, Zeitsch. f. physiol. Chem., Bd. v. 

 (1881), Sn. 152 u. 267. 



