MB. W. C. D. WHETHAM ON IONIC VELOCITIES. 
353 
= 0'00047 centim. per second, 
as the specific ionic velocity of the bichromate group. 
This is not given by Kohleausch, but we can calculate it by his method from 
known observations. Thus, Lenz has found the specific molecular conductivity of 
the solution to be 9'10 X and the migration constant was determined by 
Hittoef, and came out •502. 
By Kohlraesch’s theory (see p, 338), 
therefore, 
U = zi + u = 10352:1 
N 
= 10352 X 9-10 X 10-8 = *000942, 
V = '000942 X ’502 
= 0000473. 
This close agreement between theory and observation led me tn examine a case in 
which the specific resistances of the solutions were not the same, in order to see 
whether the method could be used when no solutions could be found with the exact 
resistance needed, I used potassium bichromate and potassium chloride, whose 
conductivities are 9’10 X 10“^^ and ll’L3 X 10“^“ respectively. If the extension of 
method is practicable, these solutions should give the s^me velocity for the bichromate 
group as the former pair—bichromate and carbonate. The galvanometer was moved, 
and, therefore, had to be regraduated. 
Ilesistauce. 
Resistance. 
O 
o 
GO = 54-0 
90 = 45-4 
65 = 52'4 
100 = 43-0 
70 = 51-0 
110 = 40-7 
75 = 49-4 
120 = 38-6 
80 = 48-0 
130 = 36-5 
85 = 46-7 
The following results were obtained— 
Therefore 
CuREENT Downwards. Motion Upwards. 
V = 4-04 4-18 4-18 4-22. Mean, 4-15. 
G= 40-0 40-0 40-2 40-2. „ 40°-l. 
= 0-00051G. 
Current Upwards. Motion Downwards. 
v= 5-19 5*18. Mean, 5-19. 
G = 50-5 49-2. „ 49°-9. 
= 0-000394. 
MDCCCXCin.—A 2 z 
