THE RELATION OF THE HEART-BEAT TO ELECTROLYTES. 183 



other, it is possible to study the action of electrolytes more simply 

 still. For in such systems the alteration of electric charge on the 

 particles is often followed by an alteration in their state of aggregation, 

 which may be manifested as an alteration in the colour of the solution, 

 or as is very usual by actual precipitation. For instance, when the 

 particles are negatively charged, as in colloidal gold or in a solution of 

 egg-white, the addition in suitable concentrations of electrolytes capable 

 of conferring positive charges on the particles causes agglutination of 

 these particles. 



Testing a large number of colloidal solutions by this method, it 

 becomes apparent that there are great differences in the relative 

 efficiencies of different ions in affecting the charge of different surfaces. 

 Thus considering the simple and the complex trivalent ions one finds 

 that many colloidal solutions are quite as readily precipitated by them 

 as by the simple trivalent ions (e.g. colloidal gold, arsenious sulphide, 

 boiled diluted egg-white, and many more), while others which are 

 readily precipitated by the simple trivalent ions are unaflected by even 

 large concentrations of the complex ions (e.g. unboiled diluted egg- 

 white, haemoglobin, etc.). Of a large number of colloidal solutions, 

 those which are very sensitive to complex as well as to simple trivalent 

 ions are found to belong to that class of colloids known as lyophobe or 

 suspensoid; those sensitive to the simple but insensitive to the complex 

 trivalent ions, to the class called lyophil or emulsoid. 



Clearly, what has been stated would indicate that the membranes 

 in the heart muscle are of an emulsoid colloidal material. This 

 indeed confirms in one special instance a conclusion drawn from 

 entirely different considerations by Martin Fischer as to the nature of 

 the body proteins in general. The study of the action of these 

 electrolytes on the heart will give more precise information than this. 

 AVhen the ratios of the activities of the simple and the complex ions 

 on surfaces of various compositions have been worked out in detail, we 

 shall be enabled to define precisely some physico-chemical constants 

 for each surface. As has been remarked, the investigations of colloid 

 chemistry have not as yet been carried far enough for this to be done, but 

 the methods are available, and the research would present no insuper- 

 able difficulty. Just as the classification of liquids of two phases into 

 suspensions, colloidal solutions and true solutions, is now recognized to 

 be an arbitrary though convenient subdivision, there being no real 

 boundaries between the classes ; so it will probably be found among 

 the colloidal solutions themselves. We shall learn in course of time 

 to describe each colloidal solution in terms of certain essential factors 

 which will include such terms as the viscosity of the phases, the 



