62 THE VEGETABLE PROTEINS 



the opposite direction, might indicate that a part of the nitrogen 

 yielded as ammonia was in the combination R CO NH CO R, 

 as recently suggested by Bergell and Feigl (588), for in this case two 

 molecules of the dibasic acid would be united to only one NH. This, 

 however, is probably not the case, for distillation of these proteins 

 with sodium hydroxide solution has given no evidence of the presence 

 of this grouping, which Bergell and Feigl have shown to be stable in 

 acid solutions but to yield ammonia on boiling with alkalies. None of 

 the other proteins, when distilled with alkali, gave any indication of 

 this diamide binding, and we have, as yet, no reason to suppose that 

 it occurs in the protein molecule. 



This marked agreement between the ammonia as determined and 

 that calculated for the proteins of seeds, other than those of the wheat 

 and the pea, indicates that this ammonia exists in these proteins as 

 amide nitrogen in combination with one of the carboxyl groups of 

 the dibasic acids. 



Nitrogen Converted into Ammonia by Alkaline Hydrolysis. 



Cystine and arginine are the only known decomposition products 

 of the proteins which are not stable in alkaline solutions. Arginine, 

 theoretically, should yield one-half of its nitrogen as ammonia on 

 boiling with fixed caustic alkalies. If the proteins yield no other pro- 

 ducts sensitive to alkalies, the amount of nitrogen which they should 

 give as ammonia, when distilled with a strong solution of sodium 

 hydroxide, ought to be equal to the sum of their amide nitrogen and 

 one-half the nitrogen of the arginine which they contain. 



Experiments by Osborne, Leavenworth and Brautlecht (364) show 

 how some vegetable proteins behave when subjected to alkaline hydro- 

 lysis. One gramme, air dry, of each of the proteins given in the table 

 below was distilled with 300 c.c. of decinormal sodium hydroxide 

 solution, and when 200 c.c. had distilled over, the distillate was titrated. 

 The residual solution was then made up to 300 c.c. with decinormal 

 sodium hydroxide solution and the distillation repeated. The solution 

 was then again made up to 300 c.c. with water and again distilled, the 

 process being repeated until no more ammonia came over. The re- 

 sults obtained are given in the following table: 



