104 



PHYSIOLOGICAL CHEMISTRY. 



(5) Dissolve the remainder of the edestin in 0.2 per cent hydro- 

 chloric acid and preserve this acid solution for use in the experiments 

 on proteans (see page 109). 



FIG. 33- 



EDESTIN. 



TESTS ON EDESTIN FILTRATE. (i) Influence of Protein Pre- 

 cipitants. Try a few protein precipitants such as nitric acid, tannic 

 acid, picric acid and mercuric chloride. 



(2) Biuret Test. 



(3) Coagulation Test. Boil some of the filtrate in a test-tube. 

 What happens ? 



(4) Saturation with Sodium Chloride. Saturate some of the 

 filtrate with solid sodium chloride. How does this result differ 

 from that obtained upon saturating egg albumin solution with solid 

 sodium chloride? 



(5) Precipitation by Dilution. Dilute some of the filtrate with 

 10-15 volumes of water. Why does the globulin precipitate? 



Glutelins. 



It has been repeatedly shown, particularly by Osborne, that after 

 extracting the seeds of cereals with water, neutral salt solution and 

 strong alcohol, there still remains a residue which contains protein 

 material which may be extracted by very dilute acid or alkali. 

 These proteins which are insoluble in all neutral solvents, but readily 

 soluble in very dilute acids and alkalis are called glutelins. The 

 only member of the group which has yet received a name, is the 

 glutenin of wheat, a protein which constitutes nearly fifty per cent 



