554 



Professor Svante ArrJienius 



[June 3, 



possibly be caused by the asbestos of the diaphragm, or by the hydro- 

 gen. V. Than, therefore, made a diaphragm of sal-ammoniac, and 

 substituted nitrogen for hydrogen, but the effect was the same. 



These experiments were performed in the years 1862 and 1864. 

 They were based on the doctrine of dissociation, which was at that 

 time (1857) worked out by Ste. Claire-Deville, and developed by his 

 pupils. From the most ancient times use was made of the fact 

 that limestone at high temperatures gives off carbonic acid, and that 

 quicklime remains. This and similar processes were studied by 

 Ste. Claire-Deville. He found that the same law is valid for the 

 pressure of carbonic acid over limestone and for the pressure of 

 water vapour over liquid water at different temperatures. On these 

 fundamental researches the theory of dissociation was based, a theory 

 which has subsequently played an ever-increasing role in chemistry, 

 and whereby a broad bridge was laid between physical and chemical 

 doctrines. A B 



a If ci H ci J£ a K OK 



000®0€)00 00 



Cl KClKaKCLKCl K 



o oooooo-oo o 



Cl CIK a K Cl K CIK 



o oooooooo 



Fig. 2. 



At almost exactly the same time we find in the writings of 

 Clausius on the conductivity of salt solutions the first traces of an 

 idea that salts or other electrolytes may be partially dissociated in 

 aqueous solutions. Buff had found that even the most minute electric 

 force is sufficient to drive a current through a solution of a salt. 

 Now after the scheme of Grotthuss, at that time generally accepted, 

 the passage of the electric current through a solution is brought 

 about in such manner that the conducting molecules, e.g. of potassium 

 chloride (KCl), are divided into their ions, which combine again with 

 one another in the following manner. At first, as the current is 

 closed, the electrode A becomes positive and the electrode B nega- 

 tive. All the conducting molecules KCl arrange themselves so 

 that they turn their positive ions (K) to the negative electrode B, 

 and their negative ions (Cl) to the positive electrode A. After this, 

 one chlorine ion is given up at A and one potassium ion at B, and 

 the other ions recombine, so that the K of the fi.rst molecule takes 

 the Cl of the second molecule, and so on (Fig. 2). Then the mole- 



