68 THE PROTEINS OF THE WHEAT KERNEL. 



600 cc. of water that is, in alcohol of 60 per cent by volume. Although 

 the solution was somewhat turbid, nothing was deposited, even on long 

 standing. 300 cc. of water were then added to the solution, making the 

 alcohol 50 per cent, but still nothing separated. The strength of the alcohol 

 was therefore raised to 75 per cent by adding 1800 cc. of absolute alcohol, 

 and a very large precipitate, A, at once separated. By adding 2000 cc. of 

 absolute alcohol to the clear solution from which A separated another large 

 precipitate (B) was produced, and in the filtrate from B a third precipitate 

 (C) resulted, when a further large quantity of absolute alcohol was added. 

 This last product weighed 20 grams and constituted only 10 per cent of the 

 total protein. The solution from which C separated contained only traces 

 of protein, and C, therefore, represented the fraction of the whole protein 

 soluble in the strongest alcohol, and should consequently contain much 

 " gluten-fibrin." In 17.5 grams of this substance dried at 110 the gluta- 

 minic acid produced by decomposing with hydrochloric acid was determined. 

 By proceeding in the same manner as in the experiment last described 7.8914 

 grams of pure glutaminic acid hydrochloride were obtained, which are equiv- 

 alent to 6.2131 grams of the free acid, or 35.5 per cent. 



Nitrogen: 0.7296 gram substance, dried at 110, gave NH 3 = 5.66 cc. HC1 (i cc. HC1 



= o.oioo grain N) = 7.75 p. ct. N. 

 Calculated for C 5 H 9 NO 4 HC1, 7.64 p. ct. N. 



This result seems to furnish conclusive evidence that there is no fraction, 

 soluble in very strong alcohol, to be obtained from the alcohol-soluble pro- 

 tein of wheat gluten that is characterized by yielding a relatively small 

 proportion of glutaminic acid. 



Since Kutscher decomposed his proteins with sulphuric acid, while hydro- 

 chloric acid was used in the preceding experiments, the following experi- 

 ment was made in order to determine whether the higher yield obtained by 

 us might not be due to this fact. Accordingly 50 grams of one of the 

 preparations of gliadin, from which 37 per cent of glutaminic acid had pre- 

 viously been isolated, were boiled for 14 hours with a mixture of 150 grams 

 of sulphuric acid and 300 cc. of water. 



The resulting solution was treated with an excess of baryta and the ammo- 

 nia expelled by evaporation. The barium was then removed by an equiv- 

 alent amount of sulphuric acid and the filtered solution evaporated. Some 

 tyrosine separated, which was filtered out, and the evaporation continued 

 until the volume was quite small. On standing, an abundant quantity of 

 crystals of free glutaminic acid separated, and from the mother-liquor, by 

 further concentration and standing, a second crop of crystals was obtained. 

 After recrystallizing several times, 8.48 grams of pure glutaminic acid were 

 obtained, which contained 9.43 per cent of nitrogen. 



