138 SCIENCE PROGRESS. 



from the presence of this acid they infer the existence of 

 a carbohydrate group in the original substance. 



By obtaining nuclein bases we are able to separate 

 some of the nitrogen of nucleic acid, but a large part still 

 remains to be accounted for. In investigating thymus 

 nucleic acid Kossel and Neumann 1 have shown that by 

 dropping it into boiling water in about ten minutes it is 

 split up into its nuclein bases and a new acid, thy?ninic acid. 

 To isolate the latter the watery solution is cooled and an ex- 

 cess of barium hydrate added. It is then allowed to stand 

 for twenty-four hours when a precipitate slowly forms, which 

 consist of guanin mixed with some barium carbonate. This 

 is filtered off and the filtrate added to twice its volume of 

 alcohol when a white precipitate of barium thyminate is 

 thrown down and the adenin and cytosin remain in solution. 

 Barium thyminate is a very hygroscopic salt, easily soluble 

 in water, to which they assign the formula Ci 6 H 23 N 3 P 2 I2 Ba. 

 Thyminic acid, as prepared from this salt, differs in several 

 important respects from the nucleic acid from which it has 

 been obtained. In the first place it does not yield any 

 nuclein bases on being boiled with dilute sulphuric acid. It 

 is very soluble in water, whereas nucleic acid is only feebly 

 soluble ; it is not precipitated from its watery solution by dilute 

 mineral acids whereas nucleic acid is, both give precipitates 

 when added to an acetic acid solution of a proteid or pro- 

 peptone, but the precipitate given by nucleic acid is only 

 soluble with difficulty in dilute mineral acids, whilst that 

 of thyminic acid is easily dissolved by hydrochloric acid or 

 by many neutral salts. They consider that this thyminic 

 acid is a paranucleic acid and is probably identical with the 

 acids obtained from some of the paranucleins. It is im- 

 portant to note that in this acid the ratio of the nitrogen to 

 the phosphorus atoms is 3 : 2, whereas in nucleic acid it is 

 6 : 2, so that by decomposing nucleic acid in this way one 

 half of the nitrogen is split off in the form of nuclein bases. 



Some of the nitrogen of the thymus nucleic acid, or 

 thyminic acid, has also been obtained in the form of a 



1 Kossel u. Neumann : Ber. d. d. ckem. Gesell., Bd. 26, S. 2753, 1893 ; 

 and Zeitschr. f. physiol. C/iem., Bd. 22, S. 74, 1896. 



