Theory of Electrolytic Dissociation. 225 



constituents entering into them ; the same is true of solutions. 

 Furthermore, those properties which are approximately ad- 

 ditive in character in the ease of chemical compounds are 

 also approximately additive in the case of solutions. Ex- 

 amples of such properties are the molecular volume, molecular 

 refractive power, and molecular heat. Again, other properties 

 like, for example, the optical rotatory power, the specific 

 inductive capacity, which are not additive in chemical 

 compounds, are also not additive in the case of solutions. In 

 tact, the only distinction between a solution and a chemical 

 compound is that the latter conforms to the laws of definite 

 and multiple proportions and the former does not. But it 

 must be borne in mind that so-called pure chemical com- 

 pounds are obtained only by subjecting the total reaction 

 products to certain purifying processes, such as evaporation, 

 distillation, sublimation, crystallization, washing, extraction, 

 &c. All of these processes put the reaction products, which 

 are in general solutions (using that word in its broader sense) 

 under special duress, as a result of which there are obtained 

 as cleavage pieces of these solutions, as it were, phases whose 

 composition remains constant through a greater or lesser 

 range of temperature, pressure, and contact with other phases. 

 7 he processes of solution and chemical action are then identical 

 in character, and chemical comjjounds are merely the cleavage 

 pieces of solutions placed under special stress or duress repre- 

 sented by the so-called purifying processes. The process of 

 solution is thus the general case of the interaction of bodies, 

 union resulting when the specific attraction, commonly called 

 chemical affinity, between them is under the existing con- 

 ditions sufficient to cause an interpenetration, a fusion or 

 blending of their masses as it were. Furthermore, adhe- 

 sion, absorption, adsorption, and imbibition are also due 

 to the same specific attraction which causes solution and 

 '•hemical action. Adhesion is really to be regarded as an 

 unsuccessful attempt at solution. Thomas Graham was un- 

 questionably right when he stated that from adhesion to 

 solution and chemical action there is every stage of gradation. 

 It is scarcely necessary to add that these views were also 

 entertained by numerous other scientists of note, among 

 whom Bunsen was especially prominent. The truth of this 

 view will force itself upon the mind of any one who seeks to 

 work out the problem of solutions in the laboratory rather 

 than at the writing-desk. It needs hardly to be emphasized 

 that the recognition of the importance of the laws of definite 

 and multiple proportions, which have been found to hold in 

 so many cases of phases that maintain their composition for 

 riuL Mig. S. 6. Vol. 9. No. 50. Feb. 1905. Q 



