--------------+
| R1. | R2. |Temperature Absolute.|
+-------+-------+---------------------+
| 2.00 | 2.495 | 411 deg. |
| 1.95 | 2.40 | 399 deg. |
| 1.85 | 2.30 | 383 deg. |
| 1.81 | 2.21 | 373 deg. |
| 1.67 | 2.125 | 348 deg. |
| 1.60 | 2.00 | 333 deg. |
| 1.39 | 1.785 | 285 deg. |
| 0.945 | 1.23 | 209 deg. |
| 0.235 | 0.235 | 94 deg. |
+-------+-------+---------------------+

We see that except in the case of the lowest temperature, that of
liquid air, where there is a great drop in the velocity, the
velocities of the ions are proportional to the absolute temperature.
On the hypothesis of an ion of constant size we should, from the
kinetic theory of gases, expect the velocity to be proportional to the
square root of the absolute temperature, if the charge on the ion did
not affect the number of collisions between the ion and the molecules
of the gas through which it is moving. If the collisions were brought
about by the electrical attraction between the ions and the molecules,
the velocity would be proportional to the absolute temperature. H. A.
Wilson (_Phil. Trans._ 192, p. 499), in his experiments on the
conduction of flames and hot gases into which salts had been put,
found that the velocity of the positive ions in flames at a
temperature of 2000 deg. C. containing the salts of the alkali metals
was 62 cm./sec. under an electric force of one volt per centimetre,
while the velocity of the positive ions in a stream of hot air at 1000
deg. C. containing the same salts was only 7 cm./sec. under the same
force. The great effect of temperature is also shown in some
experiments of McClelland (_Phil. Mag._ [5], 46, p. 29) on the
velocities of the ions in gases drawn from Bunsen flames and arcs; he
found that these depended upon the distance the gas had travelled from
the flame. Thus, the velocity of the ions at a distance of 5.5 cm.
from the Bunsen flame when the temperature was 230 deg. C. was .23
cm./sec. for a volt per centimetre; at a distance of 10 cm. from the
flame when the temperature was 160 deg. C. the velocity was .21
cm./sec; while at a distance of 14.5 cm. from the flame when the
temperature was 105 deg. C. the velocity was only .04 cm./sec. If the
temperature of the gas at this distance f