PRIMARY DISSOCIATION-PRODUCTS 



55 



a cherry-red colour. Colour reactions of skatol-carboxylic acid have 

 been described by Salkowski. 1 



Diacipiperazin-Compounds. 



According to Fischer, see p. 132, diacipiperazins occur in all prob- 

 ability in the albumin-molecule. He first discovered a glycocoll-alanin 

 compound amongst the products of partially digested silk-fibrin, and 

 subsequently manufactured a similar, if not identical compound, see p. 

 127. The four diacipiperazins which Fischer has synthetised are : 



CH Q - NH. 



CH 



o- 



Diglycocoll anhydride. 



C 4 H 9 

 /C H- 



Di-alanin-anliydride. 



NH 



C 4 H 



Leucin-imide. 



j' >c = o 



X NH GW 



CH 3 



Glycin-alanin-anhydride. 



27. Ammonia, NH 3 . Nasse 2 was the first to accurately study 

 the splitting off of ammonia from albuminous substances. He as well 

 as subsequent investigators Hlasiwetz and Habermann, 3 Kossel and 

 Kutscher, 4 E. Fischer and his pupils, 5 and various others agree in 

 stating that after the dissociation of albumins by means of acids, 

 ammonium salts are always met with in the mixture of dissociation- 

 products. Hirschler, 6 Stadelmann, 7 and Kutscher 8 observed its for- 

 mation also after tryptic digestion. Ammonia ought to be regarded, 

 therefore, as a primary dissociation -product, were it not for the 

 possibility that it may be formed secondarily out of some primary 

 dissociation - product, as soon as endeavours are made to isolate 

 it by distillation with fixed alkalies. For Nasse has shown that 

 a great deal more ammonia is obtained if the dissociation of albumin is 



1 E. Salkowski, Zeitschr. f. physiol. Chem. 9. 8 and 23 (1884). 



2 0. ^asse, Pfliigers Arch. f. d. ges. Physiol. 6. 598 (1872), 7. 139 (1872), 8. 

 381 (1874). 



3 H. Hlasiwetz and J. Habermann, Liebig's Ann. 169. 150 (1873). 



4 A. Kossel and F. Kutscher, Zeitschr. f. physiol., Chem. 31. 165 (1900). 



5 See p. 20, footnote 9. 



6 A. Hirschler, ibid. 10. 302 (1886). 



7 E. Stadelmann, Zeitschr. f. Biol. 24. 261 (1888). 



8 F. Kutscher, Endprodukte der Trypsinverdauung, Marburger Habilitationsschrift, 

 Strasburg, 1899. 



