GUANIN. 381 



ciate on contact with water (Balke). It probably has the formula 

 CjHjNjO.Cu^O. As it has more imido groups than adenin and hy- 

 poxanthin, it is probable that its solubility is less than that of the 

 copper compound of these bases. 



The solutions of the hydrochlorid are precipitated by mercuric 

 chlorid and nitrate, potassium chromate, potassium ferricyanid, and 

 by picric acid. Basic lead acetate gives a precipitate only on addi- 

 tion of ammonium hydrate. 



Guanin bichromate, (CJl^'Sfi)^.Il/^rjC>j , is in composition analo- 

 gous to that of adenin, and was obtained by Wulff by adding potas- 

 sium bichromate to a hydrochloric acid solution of guanin. It 

 appears as well formed, bright, orange-colored, elongated, four-sided 

 prisms, with truncated ends. On contact with water it readily dis- 

 sociates, especially at 100°. When heated above 100° it gives off 

 water whereas adenin, which is a stronger base, does not dissociate 

 on contact with water, and is permanent at above 100°. 



Guanin metaphosphate, CjHjNjO.HPOj -|- H^O, has also been 

 studied by Wulff. It is characterized by extremely slight solubility 

 in water and in dilute acids. Pohl first observed that sodium meta- 

 phosphate gave with guanin hydrochlorid a precipitate insoluble 

 in excess of acids, but soluble easily in alkalis. Liebermann ob- 

 tained a precipitate by adding metaphosphoric acid to a solution of 

 guanin in sodium hydrate. The same precipitate, according to 

 Wulff, forms when an acid solution of guanin is treated with meta- 

 phosphoric acid. Contrary to Liebermann, the salt has a defin- 

 ite composition, and is not prone to dissociation as is the case with 

 other compounds of guanin. The precipitation of guanin is so 

 complete that in the filtrate picric acid gives no reaction, and silver 

 nitrate produces only a slight flocculent precipitate. Inorganic salts, 

 as magnesium sulphate, may prevent or retard the precipitation. It 

 forms an amorphous, porcelain-like mass which is ignited with diffi- 

 culty. Dried at 120° it still retains one-half molecule of water. In 

 the presence of water at high temperature, as in drying, a part of 

 the compound is converted apparently into the orthophosphate, so 

 that very accurate quantitative results are not possible. 



Liebermann's view that nuclein is a metaphosphate of albumin 

 containing mechanical admixtures of metaphosphates of xanthin 

 bases has been shown to be wrong. As additional evidence is the 

 fact that guanin metaphosphate is very difficultly soluble in ammo- 

 nium hydrate, while nuclein is extremely soluble in dilute ammonia. 



Guanin ferricyanid, (C^H^Np), .H3Fe(CN)5 -f- 8H,0. This com- 

 pound separates slowly, when potassium ferricyanid is added to a solu- 

 tion of the hydrochlorid, as small, bright, brownish-yellow four- or six- 

 sided prisms. At 100° it slowly loses weight, and heating for sev- 

 eral hours at 220°- 130° is necessary to expel all the water. The 

 composition of this salt is noteworthy, for one molecule of acid com- 



