420 The Biochemical Society^ England [June-September 



times added. For some time past he had adopted the method of 

 centrifugalising the bromine precipitate, mixing the residue with 

 water, and centrifugahsing again. He made a practice of separating 

 the albumoses and peptones, but agreed that in most ordinary cases 

 this was of Httle value. There were, however, on the market cer- 

 tain so-called ' f ortified ' meat extracts which contained albumoses 

 and peptones in very much larger proportion than occurred in ordir 

 nary meat extracts. With regard to the factor used for Converting 

 the residual nitrogen into ' meat-bases ' he remarked that this was 

 the only instance which he knew of in chemistry in which a factor 

 known to be wrong was used merely for convenience. 



Mr. E. Hinks remarked that the use of a factor of approximately 

 3 for calculating the * meat-bases ' f rom the residual nitrogen seemed 

 to be justified by the fact that the proportions of nitrogenous and 

 non-nitrogenous extractives thus obtained were about equal, this 

 being what one would expect in the case of such a product as meat 

 extract. 



Dr. Percival Hartley described his experience of Van Slyke's 

 method of determining amino-nitrogen, which was based on the fact 

 that when protein and protein degradation products were treated 

 with nitrous acid, nitrogen gas was given off. The results of com- 

 plete analyses of various proteins showed that the Constitution of 

 serum albumen was quite different to that of globulins, the former 

 containing a much larger proportion of lysine and of cystine than 

 the latter. Another interesting result was that the globulins exhib- 

 ited no difference in chemical composition — euglobulin and Pseudo- 

 globulin apparently being closely related. Another point brought out 

 was that the free amino-nitrogen of native proteins appeared to be 

 approximately one-half of the lysine content, which if substantiated, 

 would appear to afford a simple method of estimating lysine without 

 hydrolysis of the protein. Furthermore, the proportion of free 

 amino-nitrogen indicated to what extent the protein had been di- 

 gested or peptonised. 



Further remarks were made by Dr. Rideal, Prof. Barger, Prof. 

 Harden, Dr. G. S. Walpole, Dr. Cathcart, Prof. Gowland Hopkim 

 and the Chairman. 



