478 Intelligence and Miscellaneous Articles. 



the geometrical interpretation of the vector V_l. Its scalar 

 form would appear to have even more singular and important 

 properties and applications. But, alas for Dr. Molenbroek, Ha- 

 milton long ago said: — and his words are final: — "the old and 

 oedhstajry imaginary symbol of common algebra .... is to be 

 treated .... not as a real vector .... but as an imaginary scalar." 

 Sic transit gloria M ! 



LIX. Intelligence and Miscellaneous Articles. 



CHEMICAL ACTION AT A DISTANCE. 

 BY S. U. PICKERING, F.R.S. 



TN the Philosophical Magazine for August (p. 145) there appears 

 a paper by Prof. Ostwald bearing this somewhat theatrical 

 title : in it the author describes some experiments for which, in 

 his opinion, " a satisfying explanation can be first gained on the 

 ground of the Theory of free ions "and which, having been " worked 

 out at [his] writing-table before [he] had seen anything of the pheno- 

 mena in question .... speak," he considers, " more forcibly than any 

 polemics for the value of this theory/' The object of the present 

 note is to try and elicit some explanation as to what the difficulty 

 is in explaining, or even predicting, the facts on the old theory of 

 electrochemical action, and why they are to be regarded as afford- 

 ing any proof of the truth of the dissociation theory. 



The chief experiment is as follows : — A zinc-platinum couple is 

 placed in a solution of potassium sulphate, and on adding sulphuric 

 acid to the liquid near the platinum the acid is decomposed with 

 liberation of hydrogen while the zinc goes into solution, whereas, 

 when the acid is added to the liquid near the zinc, no action occurs. 

 The explanation of such a result appears to be perfectly simple 

 without the aid of the dissociation hypothesis. We have only to 

 remember that a zinc-platinum couple will not decompose potas- 

 sium sulphate, but will decompose sulphuric acid, and that these 

 effects will, in all probability, remain unaffected by the slight modi- 

 fication of the ordinary contacts obtaining in Prof. Ostwald's 

 experiment : also that in all salt-solutions there is a continual 

 interchange going on between the ions in contiguous molecules, 

 which interchange involves no expenditure of work. That being 

 so, the action will be represented by the following scheme : — 



Zn S0 4 |K 2 SOJK 2 S0 4 IH 2 Pt. 



No work, or only an infinitesimal amount, is done in transferring 

 the K 2 from one S0 4 to the next: no potassium sulphate is really 

 decomposed, for there are as many molecules of it present after as 

 there were before the reaction ; and the only body which is decom- 

 posed is the acid, a decomposition which we know a zinc-platinum 

 couple will effect. The following scheme shows that if the acid is 

 placed in contact with the zinc no decomposition could occur unless 

 the couple were capable of decomposing the potassium sulphate, 

 which it is not. 



