SOAPS, PROTEIN DERIVATIVES AND TISSUES 225 



versely, throughout the whole range no matter what the surface 

 values. 



And yet these remarks must not be misunderstood. They 

 do not, in the first place, diminish the value of the actual observer 

 lions made by these different authors upon various colloid systems; 

 nor do they deny that the factors they cite are not of some impor- 

 tance in some systems. The whole problem, obviously, moves 

 back to an inquiry into still more fundamental ones: what is 

 the nature of solution; what are the forces active in producing 

 and maintaining emulsions; and what is the nature of solidifi- 

 cation without or with a " solvent "? 



We do not ourselves presume to answer these questions. In 

 the matter of the nature of solution, however, we would like to 

 emphasize our growing opinion that it is much more often union 

 in quantitative relations between dissolved substance and the 

 dissolving medium with the production of new compounds than 

 is at present accepted by the " dilute solution " chemists; and 

 that, especially in " concentrated " systems, this factor becomes so 

 great that the added element of mere subdivision of one material 

 in a second, so heavily stressed in the " dilute " solutions, largely 

 disappears. 



The forces active in stabilizing a colloid system may be any 

 or all of those which make possible or give character to a " solu- 

 tion," or which permit of the stabilization of one material in a 

 second to yield either (depending upon the physical state of the 

 phases) an emulsion or a susjx'nsion. As all the facts of mutual 

 solution cannot be understood upon any purely electrical basis, 

 and as all the phenomena of cohesion, adhesion, suspension, 

 stabilization, etc., cannot at present be understood through any 

 single notion of viscosiu <urface tension or other force, neither 

 can purely chemical, purely electrical or purely surface tension 

 concepts alone " explain " the behavior of these systems. 



6. On Peptization and Coagulation 

 1 



With tin- ioVas <>f tin- priMM-ding pages in iniixl \\r \\\<\\ now 

 to c<> it. 1 1 (i group reactions characteristic of different 



proteins, to see if some simpler concepts than we now possess 



