3Q4 THE HEXONE BASES OF EGG-WHITE, 



with pancreatic juice, obtained by the injection of secretin into a 

 dog and activated by enterokinase. These hydrolyses were 

 incomplete, though continued for many hours. A complete 

 hydrolysis has been accomplished with 25% sulphuric acid. 



Methods. — The methods of separation devised by Kossel and 

 Kutscher"^, with the modifications of Kossel and Pattenf and 

 Osborne, Leavenworth and Brautlecht, J: have been employed. 

 In four out of the five determinations, the hexone bases were first 

 precipitated by phosphotungstic acid. 



Hydrolysis. — In the final experiment, 680 c.c. egg-white con- 

 taining 95-7 gm. solid matter, 89*6 gm. protein, and 1232 gm. 

 nitrogen were placed in a steam sterilizer at 100°C., with 150 c.c. 

 water and 50 c.c. sulphuric acid, for 7 hours. Then 200 c.c. 

 sulphuric acid were added, and the mixture steamed for 6 hours. 

 It was now heated to the boiling point on a sand-bath with a 

 a reflux condenser, for 69 hours. The volume was made up to 

 1 litre, and 10 c.c. were removed for the estimation of amide 

 ammonia and melanoidin nitrogen§. The results gave 1*05 gm. 

 nitrogen as ammonia, and 0*224 gm. nitrogen as melanoidin. 

 Previously attempts had been made to carry out the hydrolysis 

 with 5% sulphuric acid. Thus 39-25 gm. dried egg-white (250c.c.) 

 were boiled in 500 c.c. 5% sulphuric acid for 50 hours. The 

 biuret test was positive after 25 hours' ebullition, but at the end 

 it appeared to be negative. Two other experiments, one con- 

 tinued for 17 hours, and the other for 48 hours, were carried out. 

 In these, and also in the tryptic digest the amounts of hexone 

 bases were much too small, while the percentage of nitrogen 

 precipitated by phosphotungstic acid was too large||. Certain of 

 the final products were contaminated with bodies resembling the 



*Zeit. physiol. Chem., xxxi., S.165, 1901. 



tZeit. physiol. Chem., xxxviii,, S.39, 1903. 



J Loc. cit. 



§ Osborne and Harris, loc, cit. 



11 Nitrogen present as ammonia was expelled before the estimations were 



made. 



