224 KEPORT — 1889. 



phenomena sncli as are involved in the formation of salts generally ; and it has 

 become more than ever obvious that the solution of very many of the fundamental 

 problems of chemistry must originate in that of electrolysis. As yet, however, 

 no philosophical attempt has been made to discuss the subject except from the one 

 point of view, or even to consider the objections which have been urged against 

 the dissociation hypothesis. I have recently dwelt on the difficulty of accepting 

 the conclusion that the solvent does not play an active part in a ' Note on the 

 Determination of the Molecular Weight of Substances in Solution, especially CoUoids/ 

 in the ' Proc. Chem. Soc' of June 20th, 1889, p. 109, to which I may refer. 



In my reply to Arrhenius in the last Report I spoke of Fitzpatrick's results 

 as ' obtained with " commercial " alcohol,' adding, ' it is very important that jswre 

 alcoholic solutions should be examined.' It is pointed out to me that this may be 

 held to imply that Fitzpatrick had used very impure alcohol ; but nothing of the 

 kind was intended by me : Fitzpatrick, I know, used the best alcohol that could 

 be bought, and carefully dried it. No substance is more difficult to purify than 

 alcohol, however, and pure alcohol is probably unobtainable : what I desired to 

 imply was that experiments should be made with alcohol which had been purified 

 with every possible precaution to the ultimate attainable limit — this has never 

 been done. 



The Zeitschrift fur Phjsikalische Chemie, 1889, p. 236, contains a very brief 

 reference to the last Report of this Committee, by the Editor, Professor Ostwald, 

 who obviously entirely fails to appreciate the force of, or even to understand, my 

 objections, and who unfortunately adopts the oft-hand tone of conscious certainty 

 of the editorial ' We,' which hitherto has been altogether absent from scientific 

 discussions, but is too frequently noticeable in the joui-nal in question. In this 

 notice there is the following phrase: 'Zum Schluss wird die Anuahme, dass 

 in o-alvanischen Elementen die chemische Energie vollig in electrische Energie 

 iibergehe, trotz der vielen gegenteiligen Erfahrungen, aufrecht zu halten 

 versucht.' It would have conduced to the proper understanding of this criti- 

 cism if Professor Ostwald had quoted, however briefly, the ' gegenteilige 

 Erfahrungen.' I presume he refers to the works of Braun and of Wright and 

 his coadjutors ; but I have already shown that their conclusions cannot be re- 

 garded as satisfactory. Meanwhile an important paper by Professor E. F. 

 Herroun, ' On the Divergence of Electromotive Forces from Thermochemical Data,' 

 has appeared in the 'Phil. Mag.' (1889, 27, 209), in which it is clearly 

 shown that in calculating the E.M.F. corresponding to a chemical change from 

 thermal values, although in some cases — that of zinc, for example — the heat of 

 dissolution of the metal in the solution actually used is to be introduced into the 

 calculation, in other cases — e.g., that of silver — the heat of formation of the 

 anhydrous salt is to be chosen. This is a most valuable observation, and is in 

 accordance with the statement in my reply to Arrhenius last year, that 'R in the 

 formula C = E R was never regarded by me as simply the resistance of the solution 

 in which the interaction takes place ; it is the resistance of the circuit in which 

 interaction occurs. This latter may be quite different from the former, as, of a 

 number of substances in solution, some only may be capable of entering into the true 

 circuit of change.' It has recently been observed that considerable cooling takes 

 place during the discharge of Faure secondary cells,' and this would point to the 

 fact that not the dilute acid present in the cell, but a lower hydrate or H., SO4 

 itself, is concerned in the change — i.e., operates in forming sulphate ; and that the 

 cooling results from the dissociation of the hydrated acid. We must therefore 

 picture to ourselves the possibility of two sets of actions taking place in certain 

 cells — one set within the circuit, and contributing to the E.M.F. ; another set 

 without the circuit, and not contributing to the E.M.F. We must picture to our- 

 selves, in fact, a set of molecules swimming up from within the solution to the surface 

 of the electrode, and there interacting with the latter ; and thereafter a product or 

 products returning into the solution and becoming hydrated : as the dehydration and 



' See a paper ' On the Inherent Defects of Lead Secondary Batteries,' by Dr. 

 Louis Duncan and H. Wiegand, read before the American Institute of Electrical 

 Engineers, New York, May 22, 1889 ; printed in the Electrical World, June 16. 



