NITROGEN RADICALS 



i t 



this method does not give reliable results. This view is, however, not 

 shared by Osborne and Harris, 1 who believe Hausmann's method to be 

 a good one, and the same conclusion Giimbel has arrived at. The 

 method has also been used by Schulze 2 and Pick. 3 



The most recent and a very thorough investigation is that of 

 Giimbel, 4 which is based on the work of Osborne and Harris. 1 Giimbel 

 discusses the value of this method for determining the three groups of 

 nitrogen-radicals supposed to exist in the albumin-molecule. 



1. AMID-NITROGEN-DETERMINATION 



Giimbel tabulates the results which various authors have obtained 

 and shows how closely they agree : 



TABLE I. 



The amid-nitrogen can therefore be determined accurately by 

 Hausmann's method, as long as we do not forget that albuminous 

 substances, which are not readily attacked by acids, especially weak 

 ones, require boiling for a longer time than do those albumins which 

 part easily with their amid-nitrogen. That, on the other hand, excessive 

 action of concentrated acids, e.g. H 2 S0 4 , for very long periods will 

 induce secondary changes is also evident. The exact time at which 

 all the amid-nitrogen has been split off may be determined either by 



1 T. B. Osborne and J. F. Harris, Journ. Amer. Chem. Soc. 25. 323 (1903). 

 2 E. Schulze, Zeitschr.f. physiol. Chem. 25. 360 (1898). 



:{ E. P. Pick, ibid. 28. 219 (1899). 

 4 Theodor Giimbel, ffofmeister's Beitrcige, 5. 297 (1904). 



