On the Velocities of the Jons. 



187 



investigation on its value for solutions of different concentration led 

 to the conclusion that, in such solutions, the whole work of carrying 

 the current is done by the residual ferric chloride, which is itself 

 probably decomposed to some extent into hydroxide and acid, though 

 perhaps the proportion decomposed is not so large as in solutions 

 without an excess of ferric hydroxide, which is one of the products 

 of the decomposition. 



An experiment on the migration of acetic acid showed that the 

 velocity of the acetate group (C 2 H 3 2 ) was, at all events, very small, 

 so that, as in the case of mineral acids, the conductivity is mainly 

 due to the motion of the hydrogen. 



The following table gives the velocities of all ions which have been 

 experimentally determined : 



The values are calculated from Kohlransch's theory for the same 

 strength of solution as that used for the direct observation. In 

 the case of copper, in decinormal copper chloride solution, there are 

 no migration data for this. The velocity of the copper ion at infinite 

 dilution is given by Kohlrausch as O00031. The sum of the ionic 

 velocities of cobalt nitrate in alcohol, as calculated from the con- 

 ductivity, comes out 0-000079, and that for cobalt chloride O'OOOOGO. 

 These numbers are to be compared with the sum of the observed 

 velocities given above, namely, 0'000079 and 0'000048 respectively. 



The Society adjourned over the Whitsuntide Recess to Thursday, 

 June 13. 



