1895.] On the Velocities of the Ions. 185 



With new solutions, containing only just enough sulphate to give a 

 visible precipitate, the result was 



t>Ba = 0*000386 cm. per sec. 



Calcium. Solutions used : decinormal calcium chloride and sodium 

 chloride, the latter containing a considerable amount of sodium 

 carbonate, in order to get a visible precipitate ; this increases the 

 disturbing effect of the precipitation. 



Temperature, 18*1. Mean conductivity at 18*1, 8*91 x lO" 3 . 



Mean current, 1*08/153 ampere. Area, 0*442 sq. cm. Mean 

 velocity, 0*376 cm. in 10 minutes. 



rca = 0*000349 cm. per sec. 

 Kohlrausch gives i>ca = 0'000290 cm. per sec. 



Silver. Solutions used : decinormal silver nitrate and sodium 

 nitrate, the latter containing a little sodium chloride. 



Temperature, 17*4. Mean conductivity at 17*4, 8*96 x 10' 3 . 

 Mean current, 1'08/164 ampere. Area, 0*442 sq. cm. Mean velocity, 

 0*480 cm. in 10 minutes. 



r A g = 0*000488 cm. per sec. 

 Kohlrausch gives t'Ag = 0*000462 cm. per sec. 



The Sulphate Group (S0 4 ). Solutions used : decinormal sodium 

 sulphate and sodium chloride, the latter containing a little barium 

 chloride. 



Temperature, 15*2. Mean conductivity at 15*2, 9*69 x 10~ 3 . 

 Mean current, 1*08/246. Area, 0'430 sq. cm. Mean velocity, 

 0'257 cm. in 10 minutes. 



t- So4 = 0*000434 cm. per sec. 



Another determination in a tube whose area of cross-section was 

 0*746 sq. cm. gave 



r s< , 4 = 0*000458 cm. per sec. 



Kohlrausch gives t*s<> 4 = - 000492 cm. per sec. 



The general result goes 'to show that the ionic velocities thus 

 measured agree, within the limits of experimental error, with 

 Kohlrausch's numbers.* 



It has already been shown (' Phil. Mag.,' October, 1894) that when 

 travelling through acetates whose concentration is 0*07 normal, the 

 velocity of the hydrogen ion is about 0*000065 cm. per second, 



* It is worthy of note that all the results for kations are slightly larger than 

 indicated by theory, while the only measurement made for an anion gives a value 

 which is slightly less. This may possibly be a result of the use of jelly. 



