BY JAMES M. PETRIE. 



99 



NITROGEN IN THE VARIOUS EXTRACTS. 



It is noteworthy that a comparatively large amount of the 

 protein is dissolved out by water alone. According to 

 Osborne, it may contain proteoses, albumins, and globulins. 

 From the amount of ash present, it is apparent that the 

 addition of distilled water to the seeds is equivalent to a 

 dilute saline solution, so that more than the real water- 

 soluble proteins is obtained in the extract. 



The alcoholic extract was treated with ether, but no pre- 

 cipitation followed, showing the entire absence of alcohol- 

 soluble proteins. 



It was observed that the clear saline extracts, after stand- 

 ing for some time, increased in acidity, and gradually de- 

 posited part of the proteins in an insoluble form. This 

 appears to be caused by the combination of the acid and 

 protein, forming an insoluble salt. 



Osborne* has shown that a large number of proteins in 

 plants possess more pronounced basic properties than acidic. 

 They can easily form salts with the organic acids of the 

 extracts. The salt-extracts were all found to be distinctly 

 acid to litmus, and much more acid in reaction towards 

 phenolphthalein. Now these insoluble salts of protein, 

 formed during the extraction, may be redissolved by careful 

 titration with sodium hydroxide, to the phenolphthalein 

 neutral point. We then obtain the sodium salt of the organic 

 acid, and the protein is set free in a form soluble in the saline 

 solution. This, by the careful titration of the salt-extracts 



(*) Journ. Amer. Chem. Soc. 1902, p. 39, 



