140 CHEMICAL STATICS 



limited solubility in water and free egg-albumin is miscible with 

 water in all proportions.* 



(b) This compound is of the same molecular weight in all of the 



C 

 solutions investigated, otherwise the ratio -^ would include a 



factor expressing the relation between the molecular weight of the 

 compound and the excess of AgNOa in its saturated solution. Also 

 the constancy of C (i.e., the constancy of a) shows that it is always 

 the same substance that is present in solution at the moment 

 preceding precipitation. 



(c) This compound is probably not ionized, since Jahn's law 

 applies only to the influence of electrolytes upon the solubility of 

 non-electrolytes . 



(d) The quantity of NO 3' bound by the protein just before 

 precipitation must be the same as the quantity of Ag+ which is 

 bound by it at the same moment, otherwise the concentration of 

 silver ions in its saturated solution would not be the same as that 

 of the NO3' ions. 



All of these conclusions obviously answer to the formation of 

 the electrically neutral compound: 



H 



I 

 HaN.R.COAg.N.R.COO 



I 



NO3 



and its precipitation. 



The last of the above conclusions also agrees with the finding 

 of Bonamartini and Lombardi (22), that in neutral solutions egg- 

 albumin binds the entire CUSO4 molecule to form an insoluble 

 compound, although in alkaline solutions it binds an excess of 

 copper, forming a soluble compound. 



Rohmann and Hirschstein (105) have described compounds 

 of casein with silver, or silver nitrate, formed by acting upon 

 solutions of casein, neutral to phenolphthalein, with excess of 

 AgNOs. The resultant precipitate when prepared from solutions 

 of sodium caseinate contained 85 X 10"^ equivalents of silver per 

 gram, while that prepared from ammonium caseinate contained 

 77 X 10-5 equivalents of silver. It will be recollected (Cf. Chap. 

 V) that at neutrality to phenolphthalein casein neutralizes 80 X 



* For it not only dissolves in water, but swells in water. Cf. Chap. XII. 



