EXPERIMENTAL. 65 



acid when decomposed by boiling with strong hydrochloric acid, determina- 

 tions of the quantity of glutaminic acid obtained from various fractions 

 have been made. 



The first difficulty encountered in examining the evidence that has been 

 offered respecting the existence of several alcohol-soluble proteins in wheat 

 flour lay in the impossibility of following Ritthausen's directions for pre- 

 paring these, since many evidently important details are omitted in the 

 description of his methods. 



Kossel & Kutscher state that their products were made according to Ritt- 

 hausen's directions, but give no details, nor do they state which method 

 they employed. Kutscher concludes another paper by the statement that 

 ' ' the wheat gluten consists of gluten-casein wholly insoluble in cold 60 per 

 cent alcohol ; gluten-fibrin, but little soluble, and gliadin, easily soluble in 

 cold 60 per cent alcohol." 



Although the writer has made a very large number of preparations repre- 

 senting fractions of this protein substance dissolved by alcohol of various 

 degrees of strength, he has never obtained any that were not either com- 

 pletely soluble in cold alcohol of 60 per cent by volume, or else contained 

 such insignificant quantities which did not dissolve that he has found it 

 impossible to make from them a preparation of * * gluten-fibrin ' ' suitable 

 for further examination. He has, therefore, been unable to repeat the 

 work of Kossel & Kutscher and is entirely at a loss to understand how their 

 preparation of " gluten-fibrin " was obtained. 



Konig & Rintelen describe their procedure in more detail. These inves- 

 tigators extracted wheat gluten with absolute alcohol, added ether to the 

 alcoholic extract, and united the precipitate produced with the extracted 

 gluten. This latter was then extracted with 65 per cent alcohol, and to the 

 extract alcohol was added until the mixture contained 88 to 90 per cent of 

 alcohol. 



After decanting from the precipitate that had formed, the solution was 

 filtered clear and evaporated to dry ness on the water-bath, finely pulverized, 

 and extracted with ether to remove fat. As all of the fat could not be thus 

 removed, the mass was again dissolved in alcohol, to which some potassium 

 hydroxide was added, and this solution shaken out several times with ether. 

 The weakly alkaline solution was then exactly neutralized with hydrochloric 

 acid and evaporated on the water-bath. The product thus obtained was 

 their "gluten-fibrin." 



The precipitate produced by 88 to 90 per cent alcohol was washed with 

 alcohol of the same strength and dissolved in a little 65 per cent alcohol. 

 From this one-half of the alcohol was distilled off and the residual solution 

 cooled, when a precipitate separated. From this the solution was decanted, 

 leaving a mass of gliadin. The solutions which remained from several such 

 5 



