210 PROCEEDINGS OF SECTION B. 
Exp. Il. =! Cs Cl. Temp. 14.6°. 
1.5 1.6 22 m6 1.07 
2 2.15 31 de 1.07 
2.5 2.7 40 1.08 
3 3.2 49 1.07 
3.5 3.75 60 1.07 
+ 4.3 71 1.08 
4.5 4.85 83.5 1.08 
5 5.4 98 1.08 
5.5 ae 5.95 113 1.08 
5.77 : 6.23 dee 123 si. 1.08 
Comparison of the figures of Exp. I. with those of Exp. IV. 
(both with half-normal potassium chloride jelly) shows to what 
extent the method can be trusted to give constant results ; while 
comparison of either of these with Exp. IJ. and Exp. III. proves 
that the substitution of Rb or Cs for K makes but a very small 
difference, these ions having nearly the same specific velocities. 
The contrast between these results and those got in the earlier 
series with the chlorides and sulphates of K, Na, and Li is very 
striking; for the Na travelled with only about two-thirds and 
the Li with only about four-ninths of the K velocity. These 
relative values are shown in the second column of Table II., 
that of K being taken as 100. The NH, value is quoted from 
former experiments with normal jellies, but this difference of 
concentration does not materially affect the relative ionic velo- 
city. In the third and fourth columns are given, for compari- 
son, the values calculated from Kohlrausch’s conductivities at 
18 deg. C of aqueous solutions of about half-normal strength 
(Ann. Phys. Chem., 1879, vol. 6, p. 172), and of infinite dilu- 
tion (Ann. Phys. Chem., 1893, vol. 50, p. 408). In the fifth 
column is given the relative velocities of the ions as calculated 
by Bredig from the conductivities of their salts at 25 deg. C 
(Zeitschr. f. Phys. Chem. 1894, vol. 13, p. 242). Baur 
(Zeitschr. f. Phys. Chem., 1895, vol. 18, p. 183) calculated some- 
what higher values for Rb and Cs; but Boltwood’s calculations 
(Zeitschr. f. Phys. Chem., 1897, vol. 22, p. 132) practically con- 
firm those of Bredig. It must be remembered that the relative 
values of velocities in half-normal jellies may well differ some- 
what from those found in aqueous solutions of infinite dilution. 
TABLE II. 
Relative Velocities of the Ions of the Alkali Metals. 
Found. - ———Calculated.—— —_— ~ 
In © Jelly. In = Solution. In Infinite Dilution. _ 
2 iohitehanei. Kohlrausch. Bredig. 
Day, os 44.7 44 54.5 57.4 
Ma... a 65.7 65 68.2 69.7 
es: ate 100 100 100 100 
Rb... oe 102 a — 104 
Cae. Ste 101 ~- — 104 
[NH, ihe 100 98 100 39:7] 
