a Williams 207 



and then to saturate it with hydrochloric acid gas in order to obtain 

 glutaminic acid hydrochloride. The yield obtained in this manner is 

 always very unsatisfactory, — much more of the hydrochloride can 

 be separated before esterification. A new method^ worked out by 

 Foreman^, was employed for the treatment of the filtrate from the 

 barium aspartate, which was carried out as follows: The alkaline 

 solution was concentrated in vacuo down to 200 c.c, and alcohol added 

 until no further precipitate was obtained. This precipitate consists 

 mainly of the barium salts of glutaminic and aspartic acids (only the 

 racemic aspartic acid is removed by the barium). The precipitate 

 was filtered oH, washed with alcohol, and the barium removed quanti- 

 tatively by means of sulphuric acid. The filtrate was strongly acid, 

 showing the presence of either glutaminic or aspartic acids or both. 

 Cold aqueous phosphotungstic acid solution was now added to the 

 concentrated filtrate to remove basic impurities. Excess of baryta 

 was added to the filtrate to remove excess of phosphotungstic acid, and 

 the excess of baryta removed quantitatively by sulphuric acid. The 

 clear filtrate was evaporated to dryness and the residue extracted with 

 cold glacial acetic acid. This removes further impurities. The residue 

 thus obtained weighed 4-1 grms. 



0*1520 grm. gave 13-3 c.c. nitrogen at 15° C. and 762-4 mm. 



- 0-01573 grm. N 

 = 10-35 per cent. N. 



Glutaminic acid contains 9-53 per cent. N, and aspartic acid 10-53 

 per cent. The substance obtained must be practically all aspartic 

 acid; it gave the pyrrole reaction, however, when heated with zinc 

 dust, and tested Avith a pine shaving, showing the presence of some 

 glutaminic acid. Calculating the proportion of glutaminic acid present 

 from the N content, we find that 18 per cent, should be present. 



10-35 - 9-53 , ^^ _ :82 , ^^ _ 82 % aspartic acid, 

 10-53 - 9-53 ^ ^^^- 1 ^ ^"" ~ 18 % glutaminic acid. 



The 4-10 grms. obtained may be looked upon as made up of 0-74 

 grm. of glutaminic acid and 3-36 grms. of aspartic acid. This brings 

 the percentage of aspartic acid in the protein up to 2-75 and gives 0-26 

 per cent, as the number for glutaminic acid. 



The alcoholic filtrate from the precipitate of barium salts was 

 evaporated down in vacuo, taken up in water, and the barium removed 

 by addition of excess of sulphuric acid. The barium sulphate was 



1 Biochem. Journ. viii, 5, 463. 



