GUANINE. 173 



hyperuric acid by Unger,) is obtained by digesting for 24 hours, 

 at a temperature of 125, 3 parts of guanine, 5 of chlorate of potash, 

 5 of water, and 30 of hydrochloric acid ; it crystallises in short 

 rhombic prisms with oblique terminal surfaces, is devoid of colour, 

 odour, and taste, reddens moistened litmus, is slightly soluble in 

 water and in acids, but dissolves freely in the caustic alkalies and 

 their carbonates, and on dry distillation yields hydrated cyanic acid, 

 together with water and carbon. 



Preparation. Guanine was obtained by linger from guano, 

 which he digests with diluted milk of lime till the fluid, when 

 boiled, no longer appears brown, but assumes a faint greenish- 

 yellow colour; it is then filtered and treated with hydrochloric 

 acid ; in the course of a few hours the guanine, with a little uric 

 acid, separates ; the sediment is then dissolved in hydrochloric 

 acid, from which it is deposited in a crystalline form as a hydro- 

 chlorate ; from this the guanine is finally separated by ammonia. 



Tests. Guanine is especially to be distinguished both from 

 xanthine and from uric acid by its forming distinctly crystallisable 

 salts with acids. Moreover, the difference of its behaviour with 

 nitric acid is quite sufficient to prevent it from being mistaken for 

 uric acid. 



Physiological Relations. 



Occurrence. Unger has, as we have already mentioned, found 

 guanine in guano (the excrements of certain sea fowls) ; it has 

 recently also been found in the excrements of spiders by F. Will 

 and Gorup-Besanez,* who think it very probable that this substance 

 occurs in the green organ of the river craw-fish, and in the Bojanian 

 organ in the fresh-water mussel. 



If the constant occurrence of this substance in the urine, which 

 Strahl and Lieberkuhnf regarded as xanthine, (but which, from its 

 solubility in hydrochloric acid, would rather seem to be guanine,) be 

 confirmed by further investigations, we should have to classify 

 guanine among the general products of excretion of the animal 

 organism. 



Origin. From everything connected with the occurrence of 

 guanine there can be no doubt that, like the nitrogenous compounds 

 to which it is allied, it is a product of the metamorphosis of the 

 nitrogenous matters of the animal body. Nothing is, however, 



* Gelehrte Anz. d. k. bair. Ak. d. Wiss. 1848, S. 825-828, [and more fully in 

 a memoir *' on guanine as an essential constituent of certain secretions of the in- 

 vertebrata," in Ann. d. Ch. u. Pharm. Bd. 69, S. 117. G. E. D.] 



t Op. cit. 



