MR. W. C. D. WHETHAM ON THE VELOCITIES OF THE IONS. 519 
We must, therefore, look for some other explanation of the velocity phenomena. 
If ferric hydrate be dissolved in ferric chloride solution, a red liquid is obtained. 
When it is remembered that the ferric acetate solution contains ferric hydrate, it is 
evident that a motion of the colour boundary would be obtained if this ferric hydrate 
were carried through the solution, either by its being attached to the kation, or by 
a motion similar to that observed in the case of light non-electrolytic particles 
suspended in water. 
Ferric hydrate can be obtained in a soluble form by dialysing a solution of ferric 
ehloride. The ferric chloride solution is placed in a glass cylinder, the lower end of 
which is covered by a sheet of parchment paper. The cylinder is then suspended in 
such a manner that the lower end is just below the surface of a large volume of 
distilled water. At the end of several days, nearly all the hydrochloric acid is found 
to have passed into the water, leaving the iron behind as a brown solution of ferric 
hydrate. A solution prepared in this manner was found to have a concentration of 
00044 gram.-equivalent per litre of chlorine, and 0°0652 gram.-equivalent of total 
iron. Its conductivity was, in C.G.S. units, 7°83 x 107%, which gives for the iron a 
molecular conductivity of 120 X 107}, a value much below the normal. If, however, 
we suppose that it is only the ferric chloride remaining in the solution which is 
active, and calculate the molecular conductivity from the amount of chlorine, we get 
1780 X 10~%—a number nearly equal to that for the ordinary ferric chloride solution 
of equivalent strength. 
A series of conductivity measurements of this solution was made at different 
dilutions, and then two similar sets for ferric chloride. In the following Table the 
results are compared, 

| 







| Dialysed iron. Ferric chloride. 
os poe ts of | Molecular conductivity | Concentration in gram.- | Molecular conductivity 
a rs aa ag at 18°. equivalents per litre. at 18°. 
chlorine per litre. 
0:00968 1445 x 10718 
| 0:0044 1780x1078 
0:00088 2255 ss, 
0:000353 2575, 
0:000176 2580 __,, | 0:000131 2690 __,, 
| 0:0000968 2747, 
| ¢ 0:0000506 2250 ,, 
0-0000352 WAY eg 
00000176 LONG 4; 
| 

0:00000968 Omnis 


The molecular conductivities are corrected for the conductivity of the re-distilled 
water used (2°97 X 10~), and reduced to 18°, 
