142 Mr. W. Sutherland. [July 26, 



the coagulative powers of chlorides of mono-, di-, and tri-valent ions on 

 arsenious sulphide to be as 1 : 30 : 1650, the common logs of which are 

 0, 1*477 and 3*217, which fall nearly into the linear form 1*564 (V—l). 



The data of Linder and Picton for the corresponding sulphates on arsenious 

 sulphide are as 1 : 35 : 1023, whose logs are 0, 1*544, and 3*01, which may 

 be written 1*515 (v— 1). 



The present theory, then, lends itself well to an explanation of this 

 remarkable law. 



In the chemistry of globulin, the prominent fact is that salt solutions 

 dissolve from a suspension an amount nearly proportional to the original 

 total strength of the suspension. According to the present theory, the 

 explanation is as follows : Just as ions by their elective force draw out the 

 ineffective doublets of molecules, which they cause to join up as semplars,. 

 they can, under suitable energy conditions, break the doublets joining the 

 semplars, which they liberate as molecules. For example, if a crystal of 

 our imaginary colloid NH 3 were dissolved in HC1, the action would be one 

 in which the ions H and CI would break the doublets joining the semplars 

 NH3, and would join on to form NH 4 C1. This I take to be a representation 

 of the solution of globulin in acids, the action of salts being not so simple. 

 It is a corollary of the coagulation of colloids by electrolytes. The same 

 electric actions that build up a coagulum can sometimes pull it down, 

 especially if the operating ions can step into places which make the total 

 chemical potential energy smaller- than before. Now the number of semplar 

 doublets in a globulin suspension which the ions can break will either be the 

 total thereof or a certain fraction of the total. In the former case we should 

 have solution of the colloid in the ordinary way, as by acids. In the latter 

 case the ions will only break those doublets which can be made unstable by 

 the particular attacking force of ions used. Hence the fraction of a globulin 

 particle dissolved by a given solution will have a definite value, and the 

 amount of globulin dissolved will be proportional to the total number of 

 particles, that is, to the original concentration of the suspension. This is the 

 explanation of the most striking experimental result brought out by 

 Hardy and Mellanby. We now proceed to give the corresponding interpre- 

 tation of equation (1) deduced from Mellanby's experiments. Let us denote 

 the semplar of globulin by G. The simplest possible formula for the semplar 

 at the moment of its detachment is bGf • Then either # and \> can coalesce 

 to form an ineffective doublet, leaving G as a molecule, or if ions like Na and 

 CI are present, their electric charges will link them on, giving NafbGJffcCl, or, 

 more briefly, NaGCl. Now the fact that about 150 times as many equiva- 

 lents of NaCl as of HC1 are required to keep a given amount of globulin in 



