proportional to the voltage. With material of only 1/500 of the activity, it was found that Ohm's law was not obeyed.
The following numbers were obtained:
Volts Current
50 109
100 185
200 255
400 335
For an increase of voltage of 8 times, the current only increases about 3 times. The current in the liquid thus tends to become "saturated" as does the ordinary ionization current through a gas. These results have an important bearing on the ionization theory, and show that the radiation probably produces ions in the liquid as well as in the gas. It was also found that X rays increased the conductivity to about the same extent as the radium rays.
Becquerel[1] has recently shown that solid paraffin exposed to the β and γ rays of radium acquires the property of conducting electricity to a slight extent. After removal of the radium the conductivity diminishes with time according to the same law as for an ionized gas. These results show that a solid as well as a liquid and gaseous dielectric is ionized under the influence of radium rays.
121. Effect of temperature on the radiations. Becquerel[2],
by the electric method, determined the activity of uranium at the
temperature of liquid air, and found that it did not differ more
than 1 per cent. from the activity at ordinary temperatures. In
his experiments, the α rays from the uranium were absorbed before
reaching the testing vessel, and the electric current measured was
due to the β rays alone. P. Curie[3] found that the luminosity of
radium and its power of exciting fluorescence in bodies were
retained at the temperature of liquid air. Observations by the
electric method showed that the activity of radium was unaltered
at the temperature of liquid air. If a radium compound is heated
in an open vessel, it is found that the activity, measured by the
α rays, falls to about 25 per cent. of its original value. This is
however not due to a change in the radio-activity, but to the
release of the radio-active emanation, which is stored in the
