PRECIPITATION OF PROTEINS BY INORGANIC SALTS 161 



Therefore 



c, - ?*; c 2 = ?*; Cl = ^ 



A A A 



Ci, 2, C 3 representing* the concentrations of monads, diads and triads 

 in their respective solutions. Thus we get for the ratios of the concen- 

 trations of equicoagulative solutions: 



JL i -i i- -i 



Ci : C 2 : C 3 = B6n : B3n : B 2n = 1 : B^n : B 3n 



_L ]_ 



Let us put B 6n = - ; the ratios can then be written: 





The reciprocals of the numbers expressing the relative concentrations 

 of equicoagulative solutions give values proportional to the coagulative 

 powers of solutions of equal concentration; so that, calling the coagula- 

 tive-powers of equivalent solutions containing monovalent, divalent 

 and trivalent ions respectively p x : p 2 : ps, we get: 



PI : p 2 : pa : = 1 : x : x 2 



Let us now take some numerical examples; 

 Putting x = 32 we get the series : 



l : 32 : 1024 



which agrees very well with Linder and Picton's results for colloidal 

 solutions of antimony sulphide : 



l : 35 : 1023 

 and putting x=40, we get 



1 : 40 : 1600 



numbers comparable to Schultze's values for sulphide of arsenic/ 



This theory obtained for some time a very wide acceptance, but 

 the difficulty attaching to it from the first was that of accounting for 

 the acquirement, by the colloid, of an electrical charge. It will be 

 recollected that the sign of the charge borne by the portion o*f the 

 colloid which is precipitated at an electrode by an electric current, is 

 reversed by changing the reaction of the solution of the colloid from 

 acid to alkaline. Obviously, therefore, the electrical charge carried 

 by the colloidal particles is determined by the acid or alkali which is 

 added to the solution, and it was tacitly assumed that the charge 

 obtaining in acid solutions was derived from the hydrogen ions of the 

 acid, while that obtaining in alkaline solutions was derived from the 

 hydroxyl ions of the alkali. But if, for example, egg-albumin acquires 

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