BY J. M. PETRIE AND H. G. CHAPMAN. 303 



nitrogen precipitable under the conditions of the experiment. 

 This amounted to 3*31% of the weight of the egg-albumin. 

 Kutscher*, who carried out similar determinations, found 27% of 

 the nitrogen present as diamino nitrogen in Eieralbumin free 

 from globulin and ovomucoid. This represented 4-19% of the 

 weight of the albumin. Osborne and Harrisf found the basic, 

 i.e., the diamino nitrogen to be 3-3% of the weight of ovalbumin, 

 and 4-16% of the weight of conalbumin, both prepared from hens' 

 eggs. Osborne, Leavenworth, and BrautlechtJ determined the 

 quantities of the individual hexone bases arginin, histidin, and 

 lysin in ovalbumin and conalbumin. They state that the amount 

 of nitrogen contained in these bases corresponds closely with that 

 precipitated by phosphotungstic acid. They therefore consider 

 that determination of nitrogen precipitated by phosphotungstic 

 acid furnishes a valuable means for controlling the results of base 

 determinations in proteins. 



Hugounenq and Galimard§ found 2-5% lysin, 2-14%arginin, 

 and no histidin in the ovalbumin of hen's egg. 



Scope of investigation. — The amounts of arginin, histidin, and 

 lysin have been estimated in the products of the hydrolysis of 

 hen's egg-white. The whole egg-white, rather than any separated 

 purified protein, has been employed since egg-white is used for 

 experimental work in nutrition and not purified protein. The 

 isolation of chemically pure proteins from egg-white is difficult, 

 and it is doubtful whether the methods of separation for pure 

 proteins are as yet satisfactory. || It is also not proven that the 

 separate proteins of egg-white are bodies of constant and definite 

 constitution. 



In certain preliminary attempts the hydrolysis has been 

 performed with 5% sulphuric acid, and, also (by one of us, H.G.C.), 



* Zeit. physiol. Chem., xxxi., S. 215, 1901. 

 + Journ. Amer. Chem. Soc, xxv., p. 346, 1903. 

 JAmer. Journ. Physiol., xxiii., p. 194, 1908. 

 §C.R., T. 143, p. 242, 1906. 

 Compare Mellanby, Journ. of Physiol., xxxvi., p. 288, 1907. 



