306 THK HEXONK BASES OF KGG-WHITE, 



Estimation of the separated hexone bases. — Two methods have 

 been employed. In the first method the amount of nitrogen 

 present in the final solution is estimated, and the quantity of 

 base calculated from this figure. The bases are isolated as salts 

 only for identification. In the second method the isolated salts 

 are used to calculate the weight of bases. 



While little can be said against the practice of calculating the 

 weight of base present in the "purified " fluids from which the 

 salts are crystallised, there is more doubt concerning another 

 practice recently introduced. Jackson and Pearce* estimated 

 the total hexone base from the amount of nitrogen precipitated 

 by phosphotungstic acid, the arginin and histidin from the 

 nitrogen precipitated by silver nitrate and baryta, and the lysin 

 from the nitrogen in the filtrate freed from silver and baryta. 

 Siegfried and Pilzf adopted a somewhat similar practice. The 

 results recorded from our experiments in Table i., show that both 

 these portions (histidin plus arginin, and lysin) contain nitrogen 

 not attributable to these substances. 



Results. — A record of two of our experiments is given in 

 Table i. The amounts of nitrogen obtained at the various stages 

 of the separation are stated. The first hydrolysis was performed 

 with 5 % sulphuric acid for 17 hours, and the second with 25 % 

 sulphuric acid for 69 hours. The first separation was conducted 

 according to Kossel & Patten, the second by the modification of 

 Osborne, Leavenworth & Brautlecht. In each case the precipita- 

 tion with silver and baryta was repeated to throw down com- 

 pletely the arginin. 



The percentage of total nitrogen present in each stage enables 

 the two results to be compared. The high figure in the first 

 hydrolysis for the precipitate with phosphotungstic acid (30-5%) 

 is due to the precipitation of polypeptides. This was evidenced 

 also by the separation with the lysin of the body resembling the 



* Journ. Expt. Med., ix., p. 520, 1907. 

 + Zeit. physiol. Chem., Iviii., S.224, 1908. 



