88 



THE; PROTEINS 



THE WHEAT 



was therefore added, and on long standing the insoluble substance gradually 

 settled, leaving a comparatively clear, yellow solution. This was then 

 siphoned off and filtered. On account of its gummy character it filtered 

 very slowly. The clear solution finally obtained was then precipitated with 

 0.2 percent hydrochloric acid, the precipitate filtered off and dissolved in 

 0.2 per cent potassium-hydroxide water. The solution so obtained was 

 filtered clear and precipitated with 0.2 per cent hydrochloric acid, the result- 

 ing precipitate washed by decant ation with water, alcohol at first dilute, 

 then gradually increased to absolute and finally with ether. Preparation 

 101 was thus obtained, having the composition shown in the following table : 



Preparations 101 and 102. 



This analysis shows that the protein extracted by potassium hydroxide 

 water from the flour which has not been in contact with water has the 

 same composition as that obtained in the other experiments. 



PROTEIN EXTRACTED BY DILUTE ALKALINE SOLUTIONS AFTER COMPLETE EXTRACTION 

 WITH DILUTE ALCOHOL OF GLUTEN FROM WHOLE-WHEAT FLOUR. 



looo grams of flour made by grinding the entire kernel of spring wheat 

 were made into a dough, washed with water till free from starch, and the 

 gluten obtained extracted thoroughly with dilute alcohol. The residue was 

 then dissolved in 0.2 per cent potassium-hydroxide water, and after the 

 resulting solution had stood for some time it was decanted from the sedi- 

 ment and precipitated by 0.2 percent hydrochloric acid. The precipitate 

 was washed by decantation with water, thoroughly extracted with dilute 

 alcohol and then with absolute alcohol, and finally with ether, and then 

 redissolved in o. 2 per cent potassium-hydroxide water. 



The solution, after filtering perfectly clear, was precipitated and the pre- 

 cipitate treated in the same manner as all the preceding preparations. When 



