418 CHEMISTRY OF THE LEUCOMAINS. 



diamido pyrimidin by the action of formic acid they prepared 6- 

 methyl purin,^ thus efifecting the conversion of a pyrimidin into a 

 purin body. Obviously the reverse change is equally possible, in 

 which case the origin of the pyrimidin bodies is easily accounted for. 

 Pyrimidin has also been synthesized by Emery.' Several amido and 

 methyl derivatives have been recently described.^ 



From the above constitution of pyrimidin it will be seen that it 

 may be looked upon as benzol, in which the nitrogen occupies the 

 meta position. It therefore has two isomers. Thus, when the 

 nitrogen is in the ortho position pyridazin results ; when in the para 

 position pyrazin. 



Uracil. — From yeast nucleinic acid Kossel and Neumann in 1893 

 isolated a thymin-like substance but the amount obtained was insuffi- 

 cient for identification. Ascoli, in 1901, demonstrated that this sub- 

 stance was not thymin but the next lower homologue, C^H^N^Oj , 

 which corresponds to the hitherto unknown uracil. A similar, if 

 not identical body, with possibly thymin, is formed in the auto- 

 digestion of the pancreas (Levene, 1901) and it is probable that 

 Kutscher met with this body although he gave it the formula 

 CgHgN^O^ in the auto-digestion of yeast. Uracil has been synthesized 

 by Fischer and Boeder.* 



Uracil crysta,llizes in needles, arranged in rosettes. It does not 

 sublime as easily as does thymin. The synthetic product on rapid 

 heating becomes brown at 280° and melts at about 335° with evo- 

 lution of gas. It is easily soluble in hot, rather difficultly in cold 

 water and is almost insoluble in alcohol and in ether. It is easily 

 soluble in ammonia but it does not unite with hydrochloric or with 

 nitric acids. When treated in the same way as thymin it yields 

 Weidel's reaction. It therefore in all probability possesses the struc- 

 ture, as given above, in which case it is 2-6 dioxypyrimidin. 



A Body, CgHjN^O^, was isolated by Kutscher ° from yeast under- 

 going sterile auto-digestion. It was precipitated from the ammoni- 

 acal silver filtrate, after removal of purin bases, on neutralization 

 with nitric acid. When purified, however, the substance is not pre- 

 cipitable by silver nitrate in acid solution and is thrown down by an 

 ammoniacal silver solution but the precipitate is soluble in excess of 

 ammonia and in nitric acid. After treatment with boiling, dilute 

 nitric acid it is precipitated by silver nitrate. The amorphous pre- 

 cipitate thus obtained is soluble in boiling nitric acid and separates 

 out on cooling as fine needles. 



The substance is neutral in reaction and is precipitated by phos- 



• Beriehte, 34, 1246. 

 'Seriehte, 34, 4178. 

 'Beriehte, 34, 2812, 3362, 3956. 



* Beriehte, 34,3751,4129. 



' Zeite. physiol. (Mem., 32, 67. 



