HYPOXANTHIN. 371 



since uric acid can be readily separated from these two bases with 

 dilute acids. The separation may be useful for guanin and xanthin, 

 which are less soluble in dilute acids, and hence difficult to separate 

 from uric acid. By effecting the precipitation in cold solution of 

 the two bases, adenin can be separated from hypoxanthin. 



With acids it yields crystallizable compounds, and, like the amido 

 acids, it forms compounds with bases and also with metallic salts, 

 such as silver nitrate and copper acetate. 



The hydrochlorid, C^H^Np.HCl + Hp, crystallizes in needles, 

 and, like the nitrate and sulphate, it is dissociated on contact with 

 water. The crystalline form is characteristic and distinct from that 

 of adenin, as well as adenin-hypoxanthin. The nitrate forms thick 

 prisms or roundish masses readily soluble in water and ammonia. 

 Platinum chlorid forms a yellow crystalline double salt, having the 

 composition CjH.Np.HCl.PtCl, . 



It does not form a difficultly soluble metaphoiphate as adenin or 

 guanin (see p. 355). 



The picrate forms bright yellow prisms easily soluble in hot water, 

 which solution is not affected as that of adenin by sodium picrate. 

 According to Wulff, it possesses the formula C^^f).Q^K^(^O^fyR 

 + HjO. It is obtained by addition of picric acid to a solution of 

 adenin, or of sodium picrate to an acid solution of adenin. Depend- 

 ing on the concentration, it precipitates in greater or less length of 

 time. It is difficultly soluble in cold water ; easily in alkaline, also 

 in ammonia. The estimation of adenin or guanin by picric acid in 

 the presence of hypoxanthin is likely to give a high result. 



Hypoxanthin-lead can be prepared, according to Kriiger, by add- 

 ing a solution of hypoxanthin in sodium hydrate to a solution of lead 

 acetate. It is amorphous. 



Hypoxanthin silver, CjHjjAgjNp.HjO, forms an amorphous 

 colorless precipitate when silver nitrate is added to an ammoniacal 

 solution of the base. All attempts to obtain a compound containing 

 but one atom of silver in the molecule, corresponding to the adenin 

 compound C^H^AgN^, have failed. The above compound was first 

 prepared by Strecker, and given the formula CjH^Np.AgjO ; but 

 the former is preferable, since on heating at 120° two and a half 

 molecules of water are lost and 2Q^^kg^p + H^O (Ag = 60.2 

 per cent.) results. At 140°-150° it loses again in weight and be- 

 comes gradually gray ; on exposure to air it absorbs moisture. In 

 this form hypoxanthin can be estimated quantitatively ; the 

 presence of sodium picrate does not interfere, but chlorids, etc., do. 

 It is insoluble in hot water. The compound CjHjAg^Np.SHjO is 

 obtained in the form of microscopic needles, by treating pure hypo- 

 xanthin silver nitrate with excess of aqueous ammonia. On boiling 

 with ammonia water it is but slightly dissolved, and appears to lose 

 slowly a part of its water of crystallization. As a result of the 



