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MR. W. C. D. WHETHAM ON THE VELOCITIES OF THE IONS. 51 
This gives for the specific ionic velocity of the SO, ion, when travelling through a 
decinormal solution of sodium sulphate in agar jelly at 18°, 
Vso, = 0°0004384 centim. per sec. 
Kou rauscu finds for decinormal potassium sulphate solution in water 
Vgo, = 0°000492 centim. per sec. 
Another determination was then made in another tube having a larger area of 
cross-section = 0°746 sq. centim. 
Temperature 11°°3. Mean conductivity = 8°79 x 107%. 
Welocity = 38, -40, -41, “44, -47, -44) -48, “44, -42; 44, 44, -50. Mean = 0-438 
centim. in 10 mins. 
Mean galvanometer reading = 48°-4. Therefore y = =p : 
Therefore : 
V, = 0000388 centim. per sec., 
which at 18° gives us 
Vso, = 0:000458 centim. per sec. 
The numbers thus obtained all agree with those deduced from theory, to an 
accuracy which must be considered to be as great as the unavoidable experimental 
errors would lead us to expect.* 
Certain substances, such as ammonia and acetic acid, are known to have 
abnormally low conductivities, as long, at all events, as the aqueous solutions con- 
taining them are not exceedingly dilute. It seemed of great interest to examine 
whether the velocities were, in these cases, proportionately reduced. The result of an 
investigation on acetic acid, in which phenol-phthallein was used as indicator, has 
already been published (‘ Philosophical Magazine, October, 1894), and gave the 
velocity of the hydrogen ion travelling through an agar jelly solution containing 
0°07 gram.-equivalent of sodium acetate per litre, as 
Vi, = 0:000065 centim. per sec. 
Now the value given by Kontrauscu for the specific velocity of the hydrogen ion 
in a solution of hydrochloric acid of this concentration is 
Vu = 00030 centim. per sec., 
so that, when travelling through acetates, its speed is reduced in the ratio of 1 to 46. 
* It is worthy of remark that the velocities of all the kations measured come out larger than theory 
requires, while that of the one anion (SO,) comes out less. It is possible that this may be due to 
tke presence of the jelly. 
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