Page:Philosophical Transactions of the Royal Society A - Volume 184.djvu/357

This page has been proofread, but needs to be validated.
MR. W. C. D. WHETHAM ON IONIC VELOCITIES.
357

(After this, the velocity began to fall off, and the kathode solution (CaCl2) got thick and faintly blue, perhaps indicating that some current is conveyed by the water of crystallisation of the CoCl26H2O, which deposits a hydrate when it meets the calcium, and that some cobalt goes faster than the rest and colours the solution. Finally, the junction went the wrong way, and other secondary actions occurred. All this shows that the effect of too great concentration has not yet been eliminated.)

Taking the mean velocity while it remained constant we get , centim. per hour.

Therefore centim. per second.

Adding this to the velocity of the chlorine (viz., 0.000026) we get

0.000048 centim. per second.

The conductivity is , and on Kohlrausch’s theory this gives

0.000060 centim. per second.

Considering the difficulties of the method and the effect of too great concentration, these numbers must be considered to agree within the limits of experimental error.

The conductivity of the nitrate of cobalt is rather greater than that of the chloride. This means that the number of active molecules is larger, and that the salt more nearly approaches the normal state. We should therefore expect the agreement to be closer than in the case of the chloride.

The velocity of the cobalt was found by using cobalt and calcium nitrate solutions, the first being red, the second colourless.

Upward velocity—Means: .
UpwardDownward velocity—Means: .
Means of both directions: .

No irregularities (such as reversals, &c.) were detected with these salts. This is what would be expected from the better conductivity.

The result is

0.000044 centim. per second.

The velocity of the NO3 group can be calculated from the numbers in p. 356. The conductivity is , and this gives

0.000035 centim. per second.

Therefore

0.000079 centim. per second.