EXPERIMENTAL. 67 



has therefore determined the amount of this amino-acid which was yielded 

 by several preparations of the alcohol-soluble protein, one of which repre- 

 sented the fraction of the protein soluble in the strongest alcohol, and should 

 therefore, according to Ritthausen, consist chiefly of gluten-fibrin. The 

 amount of glutaminic acid in gliadin was first determined by boiling 100 

 grams of gliadin, equal to 93 grams moisture free, for 14 hours with 200 cc. 

 of concentrated hydrochloric acid. After standing on ice for 3 days, the 

 entire solution solidified to a thick mass of crystals, which was sucked out 

 with a pump and washed with ice-cold alcoholic hydrochloric acid. When 

 dried over sodium hydroxide, this crude glutaminic acid hydrochloride 

 weighed 58.33 grams. The filtrate and washings on concentration gave by 

 similar treatment 2.58 grams more, making the total crude glutaminic acid 

 hydrochloride 60. 01 grams. This product was then dissolved in water freed 

 from color with animal charcoal and recrystallized. After removing ammo- 

 nium chloride by boiling with a slight excess of barium hydroxide and the 

 barium with an equivalent quantity of sulphuric acid, 43.02 grams of pure 

 glutaminic acid hydrochloride were obtained, which are equal to 34.42 grams 

 of the free acid, or 37 per cent of the gliadin. 



Nitrogen: 0.5092 gram substance, dried at 100, gave NH 3 = 3.86 HC1 (i cc. HC1 = 



o.oi gram N) = 7.58 p. ct. N. 

 Calculated for C 5 H 10 O 4 NC1, 7.64 p. ct. N. 



In confirmation of these figures this determination was repeated with 

 two fractions of the alcohol-soluble protein of wheat gluten which had been 

 separated from relatively strong alcoholic solutions, and should therefore 

 have contained a large proportion of ' ' gluten-fibrin ' ' if the statements 

 respecting the solubility of this substance are correct. 



Two portions of different preparations of the air-dry substance, equivalent 

 to 18.62 and 14.65 grams dried at 110, were hydrolyzed as before, their 

 solutions saturated with hydrochloric acid, and kept for some time on ice. 

 The glutaminic acid hydrochloride which separated was filtered out, washed 

 with alcoholic hydrochloric acid, and freed from ammonia by evaporating 

 with an excess of baryta and from barium by an equivalent quantity of 

 sulphuric acid. The solution was then decolorized with animal charcoal 

 and evaporated with an excess of hydrochloric acid until crystallization 

 began. The glutaminic acid hydrochloride which separated, when washed 

 with ice-cold alcoholic hydrochloric acid and dried, weighed, respectively, 

 8.69 and 6.27 grams, equivalent to 37.33 and 34.2 per cent of free glutaminic 

 acid in the protein. 



Another attempt was made to isolate a fraction of ' ' gluten-fibrin ' ' by 

 dissolving 200 grams of a preparation representing the total alcohol-soluble 

 protein of wheat gluten in a mixture of 900 cc. of absolute alcohol and 



