SVANTE ARRHEKIUS WALKER 723 



of activity in homogeneous and in heterogeneous systems are con- 

 sidered, and sections are devoted to the behavior of molten electro- 

 lytes and to thermochemistry. He deduces the following important 

 principle : " The heat of neutralization evolved by the transformation 

 of a base and an acid, both perfectly active, into water and a simple 

 salt, is nothing but the heat of activation of water." 



After a review of anterior theories Arrhenius summarizes his work 

 thus: "We have first shown the probability that electrolytes can 

 assume two different forms, one active, the other inactive, such that 

 the active part is always, in the same external circumstances (temper- 

 ature and dilution), a certain fraction of the total quantity of the 

 electrolyte. The active part conducts electricity, and is thus in reality 

 electrolytic ; not so the inactive part. Moreover we have proved that 

 the necessary consequences of the hypothesis of Clausius and Wil- 

 liamson is that there exist continuous circular currents, in which the 

 active parts alone participate. The molecules participating in such 

 currents are necessarily decomposed according to the scheme of 

 double decomposition, new electrolytes being thereby formed. On 

 this basis we have founded a chemical theory of electrolytes, which, 

 being deduced from very probable sources, possesses also a high 

 degree of probability. This theory leads to formulae valid for chemi- 

 cal processes, formulae very conformable to those proposed by Guld- 

 berg and Waage, which have been verified in a great number of 

 instances. . . . As a provisional approximation we have assumed 

 the coefficient of activity to be equal to the molecular conductivity. 

 The numbers calculated on this hypothesis and the reactions thus 

 foreseen, agree very well with experimental facts. . . . These propo- 

 sitions and these laws are taken from the most different parts of 

 chemical science ; but as the theory agrees so well with reality on these 

 different" points, it seems probable that it ought to do so also in inter- 

 mediate regions. . . . The theory is completely free from any hy- 

 pothesis of an affinity different from physical forces, and in this re- 

 spect is preferable to all prior theories. . . . True, it may be objected 

 that the theory is only valid for electrolytes, while previous theories 

 have embraced all substances. Against this we remark that chemical 

 knowledge is mainly based on the reaction of electrolytes . . . Reac- 

 tions in general seem to manifest a considerable analogy to those of 

 electrolytes, so that one could perhaps in the future enlarge the theory 

 until it becomes, with some modification, applicable to all substances." 



Nowhere does Arrhenius mention the word dissociation, although, 

 as we have seen, the word is currently used by Lodge. The idea is, 

 of course, there, but there is no identification of the " active part " 

 of the electrolyte with free ions acting as separate molecules. The 

 theory of electrolytic dissociation is as it were in solution in this 

 memoir ; it has yet to be crystallized out. 



