GUANINE. 247 



of silver nitrate to its ammoniacal solution, there is 

 formed a precipitate, C 5 H 4 N 4 -f Ag 2 0, which is insol- 

 uble in ammonia. This dissolves in hot dilute nitric 

 acid, and, on cooling, white needles appear in the solu- 

 tion. These are a compound of sarcine with silver 

 nitrate, C 5 H 4 X 4 + N0 3 Ag. This compound is com- 

 pletely insoluble in water, and can be employed for the 

 purpose of estimating sarcine quantitatively. 



Guanine^ glycocyamine and glycocyamidine, creatine&nd. 

 creatinine bear a close relation to uric acid, but have 

 not yet been prepared from it. 



Guanine, C 5 H 5 K 5 0. Is contained in guano, the 

 changed excrements of sea-birds ; and in the excrements 

 of garden-spiders. It has besides been shown to be 

 present in small quantity in the liver and pancreas and 

 in the scales of the bleak. In pork, in a certain disease 

 (guanine-gout), concretions of guanine occur. In order 

 to prepare it, guano is suspended in water and gradu- 

 ally milk of lime added to it, boiled and filtered. This 

 is repeated until the filtrate is no longer colored. The 

 residue, which consists essentially of guanine and uric 

 acid, is boiled repeatedly with sodium carbonate, until 

 the solution no longer gives a precipitate on the addi- 

 tion of hydrochloric acid. The combined extracts are 

 then mixed with sodium acetate and hydrochloric acid, 

 until the solution shows a strongly acid reaction. 

 After washing the precipitate thus obtained, the 

 guanine may be taken up by boiling with dilute hy- 

 drochloric acid, while the uric acid remains for the 

 greater part undissolved. On evaporating the solution 

 in hydrochloric acid, guanine hydrochlorate crystallizes 

 out, from which the guanine can be separated by means 

 of ammonia. Prepared in this way, it is still impure 

 from the presence of some uric acid, which must be 

 decomposed by dissolving in concentrated nitric acid. 

 From the guanine nitrate, which crystallizes out on 

 evaporating, the base is obtained pure by decomposing 

 with ammonia. 



