516 MR. W. C. D. WHETHAM ON THE VELOCITIES OF THE IONS. 
The ratio of the conductivity of a solution of acetic acid, containing 0°07 gram.- 
equivalent per litre, to that of an equivalent solution of hydrochloric acid is 1 to 62. 
Thus the velocity of the hydrogen ion is reduced in about the same proportion as the 
conductivity. 
In order to examine the velocity of the acetate ion (C,H,O,) of acetic acid, some 
substance was needed to serve as indicator. With ferric salts, acetates give a deep 
red colour, which is also produced if the solid ferric acetate is dissolved in water. 
It is weil known that solutions of ferric chloride undergo decomposition into soluble 
ferric hydroxide and hydrochloric acid, to an amount which increases as the dilution 
gets greater, and as the temperature rises. The hydrochloric acid can, in fact, be 
separated from the hydroxide of iron by dialysis through a membrane of parch- 
ment paper. 
The electrical conductivity of an aqueous solution of ferric acetate shows that, in this 
case also, a similar reaction goes on, for it has an abnormally low conductivity, com- 
parable with that of equivalent solutions of acetic acid, just as a solution of ferric 
chloride has an abnormally great conductivity owing to the presence of hydro- 
chloric acid. 
The molecular conductivity of an aqueous solution of ferric acetate, containing 
one-tenth of a gram.-equivalent of iron in one litre, was determined by measuring its 
resistance in another cell, whose constant was found by filling it with standard solutions 
of silver nitrate and barium chloride. The conductivity of any solution could be 
found by dividing the constant, 1604 x 107%, by its observed resistance in legal 
ohms. <A volume of 10 cub. centims. of this solution was then taken, and made up to 
100 cub, centims. in a graduated flask. 
This process was repeated three times, with the following results :—The first 
column, headed 1, gives the concentration of the solution in gram.-equivalents of 
iron per litre; the second, R, gives the observed resistance in the cell; the third, T, 
shows the temperature; in the fourth are put the values of ho, the conductivity in 
C.G.S. units, that of the water being subtracted, reduced to a temperature of 18°, 
and the fifth gives k,/n, the molecular conduetivity. 




| at mal R. Tad AO) He oreacmL Se: | © jaf at 18°: 
| Cees | ras | 
El 2455 | 16:3 703 x 10-8 | 70°3 x 10-13 
‘J 2is0. | 2-2 
‘01 T2600. 9 79be= |) Seo 10 am ee 
| 001 49700: | +177 9:99 x 10-1 =)| 9 299) 
| -Q001 177000 | 166 6-74 x 10735 67 

For equivalent solutions of acetic acid, Kouitrauscu (‘ Wied. Ann.,’ 26, p. 197) 
gives the following results :— 
