58 HANDBOOK FOR BlO-CHEMtCAL LABORATORY. 



posed to the air. When the crystals are slowly heated with 

 insufficient water from a solution they become suddenly opa- 

 lescent at -j- 53 C. It is soluble in 1086 parts cold water, 

 and much more readily soluble in hot water. Adenin is 

 insoluble in ether, but somewhat soluble in hot alcohol. It is 

 readily soluble in acids or alkalies. It is more soluble in 

 "ammonia than guanin, but less soluble than hypoxanthin. 

 The silver combination of adenin is difficultly soluble in 

 warm nitric acid, and deposits crystals of adenin silver nitrate 

 on cooling. It also gives a combination with picric acid 

 which is soluble with difficulty. 



Guaniu forms an amorphous, colorless powder, but crystal- 

 lizes in very small crystals from a solution in concentrated 

 ammonia if allowed to spontaneously evaporate. It is insolu- 

 ble in water, alcohol, or ether, readily soluble in mineral 

 acids or alkalies, but with difficulty in ammonia. The HC1 

 salt of guanin crystallizes readily, and on account of its action 

 on polarized light may be made use of in the identification 

 of guanin. Picric or metaphosphoric acids precipitate even 

 very dilute solutions of guanin. The silver combination is 

 very difficultly soluble in boiling nitric acid, and deposits 

 crystals on cooling. 



UroMlin. 



Preparation. 1. Several litres of urine are acidified with 

 H 2 S0 4 , using 2 grms. for every litre; then saturated with 

 ammonium sulphate, filtered, and washed with a saturated so- 

 lution of ammonium sulphate faintly acidified with sulphuric 

 acid. The residue of urobilin is dissolved in alcohol, which 

 requires some time. The filtered alcoholic solution is mixed 

 with chloroform and a volume of water equal to the alcoholic 

 solution, well shaken together, and allowed to stand until the 

 chloroform has settled. The chloroform is removed by means 

 of a separatory funnel, and washed with twice its volume of 

 water. The clear chloroform solution is now filtered through 



