1895.] 



On the Velocities of the Ions. 



183 



formation of a slight precipitate of barium sulphate. That this did 

 not seriously affect the result was shown by making two determina- 

 tions of the velocity of the barium ion, much more sodium sulphate 

 being present in the first case than in the second. The numbers 

 obtained for the specific ionic velocity were 0'000385 and 

 O000390 cm. per second respectively. 



The influence of the jelly was examined by determining the velocity 

 of the bichromate group (Cr 2 7 ) with solid solutions of potassium 

 bichromate and potassium chloride the motion being indicated by 

 the change in colour. The result was 0'00044 cm. per second. In 

 the former paper the velocity of the same ion, measured by means of 

 aqueous solutions of these salts, came out 0'00047 cm. per second. 

 The influence of the jelly thus appears to be small, as is also indicated 

 by Arrhenius' experiments on the conductivity of such solutions 

 (' B. A. Report,' 1886, p. 344). 



The apparatus used and the method of measurement were the 

 same as in the former investigation. Two vertical glass tubes, about 

 2 cm. in diameter, were joined by a third, considerably narrower, 

 which was bent parallel to the others for the greater part of its 

 length. In this tube the jelly solutions came in contact with each 

 other, and formed a slight precipitate at the junction. When a 

 current was passed from one solution to the other, this precipitate 

 spread, and the rate at which its advancing surface moved, was 

 measured on a glass scale placed behind it, the observations being 

 made through a telescope. 



