76 THE NITROGENOUS DERIVATIVES OF THE ALBUMINS. 



formation of what I have termed the secondary nucleinic acids. 

 These contain more phosphorus than the primary acids, and may or 

 may not give rise to xanthin bases on further decomposition. They 

 may accordingly be divided into acids of the type of plasminic acid 

 and of thymiuic acid, respectively. The former result from the 

 primary acids through a splitting off of atomic groups, which are 

 free from phosphorus, but ultimately the characteristic decomposi- 

 tion-products of the primary acids result, viz., the nucleinic bases, 

 phosphoric acid, etc. 



Thyminic acid, on the other hand, is obtained from the primary 

 acids, with the possible exception of inosinic acid and guanylic 

 acid, after the separation of the nucleinic bases. For its barium 

 salt Kossel obtained the formula CjgH^NgPgO^Ba. On decomposi- 

 tion with strong sulphuric acid thyminic acid yields a crystalline 

 product termed thymin. As this substance is obtained as a con- 

 stant decomposition-product from all the primary nucleinic acids 

 which have been examined in this direction, with the exception, 

 as has been indicated, of inosinic acid and guanylic acid, Kossel 

 now divides these primary acids into thymonucleinic acids, and 

 a second group which is represented by the two exceptions just 

 mentioned. 



Thymin (C 5 H 6 K>O 2 ), according to Steudel, may be regarded as a 

 methyl-dioxy-pyrimidin, and is thus isomeric with methyl-uracil. 

 It is closely related to the ureids (barbituric acid, etc.) and the purin 

 bases (see below), and it is possible, as a matter of fact, to condense 

 isodialuric acid, which is closely related to uracil, with urea to uric 

 acid. The position of the hydrogen and oxygen atoms, as also of 

 the methyl group, in their relation to the pyrimidin nucleus, is, how- 

 ever, as yet uncertain. The relation existing between these bodies 

 may be seen from the following formula? : 



N NH N 



CH CH CO C CH 3 CH CH 



I II II! I I 



N CH NH CH N C NH V 



V ) cl1 



CH CO C N^ 



Pyrimidin. Methyl-uracil. Purin. 



The primary nucleinic acids are amorphous and possess a strongly 

 acid reaction. They are soluble in dilute solutions of the alkalies, 

 and are precipitated from these solutions, especially in the presence 

 of alcohol, by adding a slight excess of hydrochloric acid. In 

 alcohol and ether they are insoluble. In acid solutions (acetic acid) 

 they give rise to precipitates with albumins, which are apparently 

 identical with the nucleins. From the nucleins they are obtained 

 by treating with a dilute solution of sodium hydrate, which is subse- 

 quently neutralized with dilute hydrochloric acid. The separated 

 albumin is then precipitated by adding an excess of acetic acid, when 



