MR. W. C. D. WHETMAN ON IONIC VELOCITIES.
349
Current reversed at 4.0 downwards.
Galvanometer. | Time. | Position. | |||
74.9 | 6.25 | 26.9 | 27.0 = 1.45 centims. per hour. | ||
27.2 | |||||
72.8 | 11.30 | 27.2 | |||
12.45 | 29.2 | ||||
1.65 centims. per hour. | |||||
1.30 | 30.5 | 1.70 centims.„ per hour.„ | |||
1.45 | 30.9 |
Current upwards.
Galvanometer. | Time. | Position. | |||
73.9 | 2.0 | 30.9 | |||
4.15 | 27.3 | ||||
1.53 centims. per hour. | |||||
73.0 | 5.0 | 26.3 | 1.43 centims.„ per hour.„ | ||
7.15 | 23.0 |
Means going up | G. = 73°.9 | v = 1.57 centims. per hour. |
Means„ going„ down | G. =73°.9 | v= 1.60 centims.„ per hour.„ |
Means of all observations G. | = 73°.9 | |
v | = 1.59 centims. per hour. |
We get from the table of graduations to be , and find from our equation (p. 346)
.
This is for unit potential gradient on the C.G.S. system, and gives for a gradient of 1 volt per centim. a velocity of
0.000309 centim. per second.
This is the velocity of the copper ion in a solution of 0.1 grm. equivalent per litre, while Kohlrausch deduced for infinite dilution
0.00031 centim. per second.
The next case I shall describe is that of a pair of salts whose 0.1 grm. equivalent solutions have specific resistances which are nearly the same. Mr. Fitzpatrick kindly supplied me with a long list of conductivities reduced to comparable units,