ADENIN. 351 



which is decomposed by acids into histon and leuconuclein. The 

 latter in turn can be decomposed into albumin and nucleinic acid, 

 which on heating with mineral acids yields phosphoric acid, and the 

 nuclein bases (adenin, hypoxanthin) and unknown products. As 

 Kossel has pointed out, it is probable that ordinary nucleinic acid 

 is a mixture of several, since two or more nuclein bases form on 

 decomposition. The existence, however, of nucleohiston, has been 

 questioned by Bang and others. 



Adenin, when crystallized from warm or impure solutions, is 

 obtained either as an amorphous substance, pearly plates, or in the 

 form of very small microscopic needles ; from dilute cold solutions it 

 separates in long, needle-shaped crystals containing three molecules 

 of water. This water of crystallization is lost on exposure to the 

 air or on heating to 53°, and the crystals become opaque. By pre- 

 cipitating a concentrated solution of the hydrochlorid with ammonia 

 adenin may be obtained as anhydrous, small whetstone-shaped 

 crystals, which, recrystallized from hot water, form large, regular, 

 four-sided pyramids, single or bur-shaped. It is soluble in about 

 1086 parts of water at the ordinary temperature ; more easily in hot 

 water, from which on cooling it recrystallizes. The aqueous solution 

 possesses a neutral reaction. The free base is insoluble in ether, 

 chloroform, and alcohol ; soluble in glacial acetic acid, and some- 

 what in hot alcohol. It dissolves readily in mineral acids, yielding 

 well crystallizable salts. The fixed alkalis dissolve it with ease, but 

 on neutralization of the solution it is reprecipitated ; from such solu- 

 tions in alkalis anhydrous large crystals are thrown down by acetic 

 or carbonic acid (Kriiger). In aqueous ammonium hydrate it is 

 more readily soluble than guanin (which is insoluble, Schindler ; 

 somewhat soluble, Wulff), and more diflScultly soluble than hypo- 

 xanthin — a fact which is made use of to effect a separation from 

 those bases. It is but slightly soluble in sodium carbonate. 



Adenin can be heated to 278° without melting; at this tempera- 

 ture it becomes slightly yellow, and yields a white sublimate. It 

 can be completely volatilized without decomposition, by heating on 

 an oil-bath at 220° ; the sublimate consists of pure, white, plumose 

 needles of adenin, but at 250° partial decomposition occurs, and 

 some hydrocyanic acid forms. According to Fischer, when heated 

 rapidly, in a capillary in a paraffin-bath, to 360°-365° adenin sud- 

 denly melts and evolution of gas takes place. When heated with 

 potassium hydrate to 200° on an oil-bath, it yields a considerable 

 quantity of potassium cyanid. Adenin is quite indifferent to the 

 action of acids, alkalis, and even oxidizing agents. Thus, it may be 

 boiled for hours with baryta, potash, or hydrochloric acid, without 

 suffering decomposition. But when heated with dilute hydrochloric 

 acid at 135° for several days, or with concentrated hydrochloric 

 acid, in a sealed tube at a temperature exceeding 100°, adenin is 



