I9I4] A. W. Thomas 215 



wlien neutralized, does not give a precipitate with either barium 

 Chloride, calcium chloride, cadmium sulf ate, or lead acetate ; cupric 

 acetate produces a bluish crystallina precipitate, insoluble in cold 

 water; silver nitrate, a flocculent amorphous precipitate; by oxida- 

 tion is converted into lutedinic acid, which melts at 239° C. 



(23) To the filtrate from (21) dilute ammonium hydroxide 

 sol. is added until precipitation ceases, care being taken not to add 

 an excess. The sol. is iiltered and the precipitate (24), after wash- 

 ing carefully with water, is suspended in water and decomposed 

 with hydrogen sulfide, the sol. is boiled to remove the excess of 

 hydrogen sulfide, filtered, concentrated and allowed to stand. Cyto- 

 sine,^^ i£ present, will separate out in shining leaflets or scales. 



Cytosine: C4H5N3O + H2O; clear crystals, effloresce in the air, 

 become opaque, do not melt at 300° C. but darken slightly; diffi- 

 cultly soluble in cold water, quite soluble in hot water; difficultly 

 soluble in alcohol ; insoluble in ether ; water sol. is neutral, but Com- 

 pounds of definite crystalline appearance can be obtained with acids ; 

 Sulfate crystallizes in needles, hydrochloride in prisms; forms a 

 difficultly soluble picrate, crystallizing in needles ; the chloroplatinate 

 crystallizes in characteristic prisms; addition of potassium bismuth 

 iodide to an acidified water sol., forms a red micro-crystalline pre- 

 cipitate. 



(25) The neutralization precipitate from (15) is added to the 

 third portion of the neutralized filtrate and made strongly alkahne 

 with sodium hydroxide and filtered. To the boiling filtrate Fehl- 

 ing sol. is added, together with a little glucose. The sol., after the 

 precipitation is complete, is filtered while hot and the filtrate dis- 

 carded. 



The precipitate (26) is washed until neutral and, after being 

 suspended in water, is decomposed in boiling sol. with hydrogen 

 sulfide, boiled to remove excess of hydrogen sulfide, and filtered. 

 If the filtrate is not clear, the foUowing steps must be taken: the 

 sol. is evaporated to dryness on a water bath, alcohol is added, and 

 the sol. again evaporated. The residue is taken up in hot water and 

 filtered while hot. This treatment generally removes the suspended 

 copper sulfide. If it does not, very dilute nitric acid may be added. 



1* Schreiner and Shorey : Pyrimidine derivatives and purine bases in soils, 

 Journ. Biol. Chem., igio, viii, p. 385. 



