186 THE PROTEIN SUBSTANCES. 



certain conditions appear in crystals similar to creatinine-zinc chloride. 

 It is insoluble in water, alcohol, and ether. It is rather easily dissolved 

 by mineral acids and readily by alkalies, but it dissolves with great 

 difficulty in ammonia. According to WULFF 1 100 cc. of cold ammonia 

 solution containing 1, 3, or 5 per cent NH 3 dissolve 9, 15, or 19 milli- 

 grams of guanine respectively. The solubility is relatively increased 

 in hot ammonia solution. The hydrochloride readily crystallizes, and 

 has been recommended by KOSSEL 2 for the microscopical detection of 

 guanine, on account of its behavior toward polarized light. The sul- 

 phate contains 2 molecules of water of crystallization, which is completely 

 expelled on heating to 120 C., and this fact, as well as the fact that 

 guanine yields guanidine on decomposition with chlorine-water, differ- 

 entiates it from 6-amino-2-oxypurine, which is considered as an oxidation 

 product of adenine and possibly occurs as a chemical metabolic product 

 (E. FISCHER). The 6-amino-2-oxypurine sulphate contains only 1 

 molecule of water of crystallization, which is not expelled at 120 G. 

 Very dilute guanine solutions are precipitated by both picric acid and 

 metaphosphoric acid. These precipitates may be used in the quantita- 

 tive estimation of guanine. The silver compound dissolves with difficulty 

 in boiling nitric acid, and on cooling the double compound crystallizes 

 out readily. Guanine acts like xanthine in the nitric -acid test, but gives 

 with alkalies on heating a more bluish-violet color. A warm solution 

 of guanine hydrochloride gives with a cold saturated solution of picric 

 acid a yellow precipitate consisting of silky needles (CAPRANICA). 

 With a concentrated solution of potassium bichromate a guanine solution 

 gives a crystalline, orange-red precipitate, and with a concentrated 

 solution of potassium ferricyanide a yellowish-brown, crystalline pre- 

 cipitate (CAPRANICA). The composition of these and other guanine com- 

 pounds has been studied by KOSSEL and WULFF. S It also gives a com- 

 pound with picrolonic acid (LEVENE 4 ) . Guanine does not give WEIDEI/S 

 reaction . 



HN CO 



Hypoxanthine, S ARKINE, C5H 4 N 4 O, = HG C NH V = (6-oxypurine) . 



14- N>* 



This body has been found in all cellular organs and as a cleavage product 

 of inosinic acid. It is especially abundant in the sperm of the salmon 



1 Zeitschr. f. physiol. Chem., 17. 



2 Ueber die chem. Zusammensetz. der Zelle, Verb. d. physiol. Gesellsch. zu Berlin, 

 1890-91, Nos. 5 and 6. 



3 Zeitschr. f. physiol. Chem., 17; Capranica, ibid., 4. 



4 Biochem. Zeitschr., 4. 



