518 
IOWA ACADEMY OF SCIENCE Vol. XXIV, 1917 
The mean values of these have been calculated and are inserted 
for comparison. 
TABLE II. 
Transport Numbers of ttie Lithium Ion in Aqueous Solutions. 
Normality 1. — 0.1 0.5 — .05 0.1 — .01 .05 — .005 
Kohlraush 261 .31 .27 .33 . .31 .37 .33 (.39) 17 
Calc, mean .28^ .300 .340 .360 
Obs. mean .279 .322 .343 .365 
The agreement is as satisfactory as could be expected and 
confirms the applicability of this method of measuring the trans- 
port numbers of ions. 
The transport numbers of the ions in a solution are determined 
bv the relative mobility of these ions at the dilution in question. 
The mobility of an ion is in turn a function of its mass, the 
area and configuration of its surface and the viscosity of the 
solution. The variation of the transport number with the dilu- 
tion of the salt in lithium chloride solutions must be caused by 
a change in one or more of these properties of one or both of the 
ions. 
Jones and Getman 18 have shown that, starting with a concen- 
tration of 0.24 N, the molecular lowering of the freezing-point, 
produced by lithium chloride in aqueous solutions increased both 
with the concentration and with the dilution. They have also 
found 10 that the molecular elevation of the boiling-point prt^ 
duced by solutions of lithium chloride in ethyl alcohol is at all 
concentrations greater than the values calculated on the basis 
of dissociation. . They attribute these abnormal increases in the 
freezing-point lowering and boiling-point elevation with increas- 
ing concentration to “solvation.” 
The solvation of an ion undoubtedly increases both its mass 
and surface and probably also affects the viscosity of the solu- 
tion. If one of the ions of an electrolyte is more highly solvated 
than the other, dilution will affect the two ions to a different 
degree. Consequently, such an electrolyte should show a differ- 
ence in the relative mobility of the ions with varying dilution 
and therefore a corresponding change in the transport numbers. 
Conversely, a change in the transport numbers with dilution 
may be considered to be an indication of solvation. If this 
17 Extrapolated. 
18 Zeit. phys. Chem., 46, 261, 1903. 
19 Am. Chem. Jour., 32, 338, 1904. 
