156 Prof. Ostwald on Chemical Action at a Distance. 



wholly dissociated. In order that this may become possible, 

 both of the negative units of electricity of the HSO3 i° ns must 

 be removed ; they pass through the electrode to the other solu- 

 tion, where they serve to change a bromine molecule, Br 2 , into 

 bromine ions. The same result is reached when the bivalent 

 ions of the neutral sulphite, S O3, are supposed to be changed 

 into sulphuric acid according to the reaction 



S0 3 + H 2 = H 2 S0 4 ; 



for every molecular weight of sulphuric acid formed, two 

 units (of 96540 coulombs each) of negative electricity must 

 pass through the connecting wires. 



The electromotive forces which are developed when different 

 solutions act upon the same metal are not unknown ; they 

 were first extensively investigated by R. Arrott* and later by 

 A. Wright and C. Thompson f . The possibility of analysing 

 more closely the actions upon which they depend and of 

 understanding these actions in this fundamental character, was 

 first given by the consideration of the electrical relations of 

 the ions, which indeed before Arrhenius developed his so 

 extremely fruitful theory, was not carried out. 



In conclusion I wish to add that the description of some of 

 the experiments, which are communicated here, was completely 

 worked out at my writing-table, before I had seen anything of 

 the phenomena in question. After making the experiments on 

 the following day, it was found that nothing in the description 

 required to be altered. I do not mention this from feelings 

 of pride, but in order to make clear the extraordinary ease 

 and security with which the relations in question can be con- 

 sidered on the principles of Arrhenius's theory of free ions. 

 Such facts speak more forcibly than any polemics for the 

 value of this theory. 



A number of interesting phenomena, with which I have 

 met in further investigations on this chemical action at a dis- 

 tance, will be presented at another opportunity. I hope like- 

 wise, as soon as I can find the necessary time, to be able to 

 produce some pertinent quantitative measurements. I do not 

 mention this to keep others at present from the carrying out 

 of such experiments and measurements, but, on the contrary, 

 in order to express my conviction of the necessity of a search- 

 ing quantitative study of this field. 



University Laboratory of Physical Chemistry, 

 Leipsic, Germany, May 1891. 



* Phil. Mag. [3] xxii. p. 427 (1843). 

 t Journ. Chem. "Soc. 1887, p. 672. 



