EXPERIMENTAL. 71 



sirup was then poured, in a very fine stream, into a large volume of absolute 

 alcohol under rapid and constant stirring. In this way a porous mass of 

 protein was obtained which was at once reduced to small pieces and digested 

 under fresh absolute alcohol. When well dehydrated, the gliadin was 

 digested with ether, partially dried over sulphuric acid, ground to a coarse 

 powder, and then dried thoroughly over sulphuric acid. When thus pre- 

 pared, gliadin forms a snow-white, friable mass which is easily reduced to 

 a powder. 



1 100 grams of gliadin, equal to 998.6 grams dried at no c , were heated 

 with a mixture of 1000 cc. of concentrated hydrochloric acid and 1000 cc. 

 of water on the water-bath for several hours, until the gliadin had dissolved 

 and frothing had ceased. The solution was boiled in an oil-bath having a 

 temperature of 115 for 10 hours, cooled with ice, and saturated with gaseous 

 hydrochloric acid. After remaining on ice for 2 days, the glutaminic acid 

 hydrochloride that had separated was filtered out, washed with ice-cold 

 alcoholic hydrochloric acid dissolved in water, the solution treated with 

 bone-black and freed from ammonia by boiling with an excess of barium 

 hydroxide. After removing the barium with an equivalent amount of sul- 

 phuric acid, the glutaminic acid was separated as hydrochloride, and, when 

 recrystallized and thoroughly dried, weighed 374.3 grams, equivalent to 300 

 grams of free glutaminic acid. This was converted into the free acid, which 

 melted at 202 to 203. 



Carbon and hydrogen : 0.6218 gram substance gave 0.9276 gm. CO 2 and 0.3494 gm. H 2 O. 

 Nitrogen: 0.4574 gram substance gave NH 3 = 4.3 cc. HC1 (i cc. HCl = o.oi gram N). 

 Calculated for C 5 H 9 O 4 N, C 40. 78, H 6. 18, N 9.54 p. ct. ; found, C 40. 69, H 6.24, N 9.40 p. ct. 



The mother-liquor from the recrystallized glutaminic acid was added to 

 the filtrate from the first separation of the glutaminic acid, and the entire 

 solution concentrated to a sirup under strongly reduced pressure. 3 liters 

 of alcohol, previously saturated with hydrochloric acid at a low temperature, 

 were added to the sirup, and dry hydrochloric acid gas was passed into the 

 solution until it was saturated. The mixture was again concentrated as 

 before, under reduced pressure, the sirup again taken up in 3 liters of alco- 

 holic hydrochloric acid, and after standing, several hours again concentrated 

 to a sirup, taken up a third time in alcoholic hydrochloric acid, and after some 

 hours concentrated to a sirup on a bath of 40 and under a pressure of from 

 5 to 10 mm. The neutralization, extraction, and drying of the esters were 

 conducted according to the method described by Emil Fischer. 1 



The undistilled residue, after distillation A, weighed 180 grams. 



The residue which remained after extracting the esters with ether was 

 made strongly acid with hydrochloric acid, freed from sodium and potassium 



1 Fischer, Emil, Zeitschrift fur physiologische Chemie, 1901, xxxiu, p. 151. 



