EXPERIMENTAL. 97 



hydrochloric acid with silver sulphate, the solution was boiled with a solu- 

 tion of copper hydroxide and i.i grams of copper aspartate were isolated. 



Copper : 0.3991 gram substance, air-dried, gave 0.1163 gram CuO. 



Nitrogen : 0.2066 gram substance gave NH, = 1.06 cc. HC1 (i cc. HC1 =0.01 gram N). 

 Calculated for C 4 H 5 O 4 N, Cu 4^ HjO, 1 Cu 23.06, N 5.09 p. ct. ; found, Cu 23.27, N 5.13 

 p. ct. 



The filtrate from this copper aspartate, when freed from copper by hydro- 

 gen sulphide and concentrated to small volume, yielded, by fractional crys- 

 tallization, 4.35 grams of nearly pure serine. 



Carbon and hydrogen: 0.2847 gram substance gave 0.3559 gram CO, and 0.1751 gram 



H 2 O. 

 Calculated for C 3 H 7 O 3 N, C 34.29, H 6.67 p. ct. ; found, C 34.09, H 6.83 p. ct. 



This substance browned at about 2 13 and decomposed to a brownish mass 

 at about 243. 



RESIDUE FROM DISTILLATION. 



The residues which remained after distilling off the esters weighed 304.5 

 grams. These were dissolved in hot alcohol, and from their united solutions 

 3.16 grams of substance separated on cooling. The filtrate from this sub- 

 stance was evaporated under reduced pressure, the residue dissolved in water 

 and saponified by heating with an excess of barium hydroxide for 9 hours. 

 After removing the barium quantitatively, the solution was concentrated and 

 saturated with hydrochloric acid. On standing for some time on ice, 38.25 

 grams of glutaminic acid hydrochloride, which melted at 198, were ob- 

 tained. This was equivalent to 30.64 grams of free glutaminic acid, and, 

 with that previously isolated, made a total of 193.04 grams, or 23 per cent 

 of the glutenin. The glutaminic acid hydrochloride was decomposed with 

 an equivalent quantity of potassium hydroxide, and the free glutaminic acid 

 was recrystallized from water. It melted at 202 to 203 with effervescence. 



Carbon and hydrogen: 0.3504 gram substance, dried at 110, gave 0.5275 gram CO, 



and 0.2003 gram H,O. 

 Calculated for C 5 H 9 O 4 N, C 40.82, H 6.12 p. ct. ; found, C 41.06, H 6.35 p. ct. 



RESIDUE AFTER ESTERIFICATION. 



The residue which remained after the third esterification and extraction 

 of the esters was treated in the same way as the corresponding residue from 

 gliadin (p. 77), and the solution, freed from all mineral salts and bases 

 precipitable by phosphotungstic acid, was concentrated under reduced press- 

 ure to a small volume and then left for some time over sulphuric acid. 



^itthausen, Die Eiweisskorper, etc., Bonn, 1872, p. 219. 

 7 



