424 Mr. W. B. Hardy. [Apr. 9,; 



the middle of the line WG. In other words, the isotherms of blood globulins, 

 over the region where we have any information to guide us, are of the form; 

 shown in fig. 4. 



S 



This is as far as the known facts carry us. It now remains to compare 1 

 the system with a similar one. Such a one is found in water, sodium 

 chloride, and succinic nitrile, which has been studied by Schreinemakers.* 

 In both there is a pair of immiscible bodies, salt, and globulin, or salt and 

 succinic nitrile, each of which is partially miscible with the third substance, 

 water. Fig. 4, A and B are two isotherms reproduced from Schreinemakers' 

 paper. It is obvious that, in all essential features, they resemble the 

 isotherms for globulin-salt-water already given. 



It is clear, from this comparison and from the low viscosity, that globulin- 

 salt-water is a system showing few abnormal features. It manifests decisive 

 points of equilibrium, which resemble those in a comparable and purely 

 crystalloid system. The other two globulin systems are as decisively 

 abnormal, especially in the high viscosity, and the absence of definite- 

 transition points, and it is significant that, regarded from the purely physical 

 standpoint, the essential difference should be the presence in the latter of> 

 large molecular aggregates, each carrying an electric double layer. 



The presence of internal electrified surfaces adequately accounts for the 

 high degree of inertia which obscures the transition points. What is the 

 source of the electrification ? In all cases in which it can be traced, the 

 charge is due to molecular interaction of the type classed as chemical, and of 

 that particular chemical type associated with the decomposition of neutral 

 electricity, to which the name " ionisation " has been given. Burtonf clearly 

 shows that metals form hydrosols because they react with the solvent to form 

 hydrides or hydroxides. Acid globulin, alkaline globulin, and soaps are salts, 



* 'Zeits. f. Physik. Chem.,' vol. 23, p. 417, 1897. 

 t ' Phil. Mag., ; April, 1906. 



