232 
MR. J. ZELENY ON THE VELOCITY OF THE IONS 
It is seen that the value of the velocity is greater for the negative ions in all cases 
except for moist carbonic acid. In comparing the values for the different gases, the 
temperature at which the observations were taken must he taken into consideration. 
At the time the writer* * * § determined the ratio of these velocities, the influence of 
moisture being unknown, the gases used were not dried, and so the values obtained 
were between those given above for the dry and the moist gases. Of the gases used 
in the former experiments, which were not used in these, the ammonia gas used had 
been passed through two long tubes of calcium oxide, the acetylene gas had been 
passed through a long tube of calcium carbide and the nitrogen monoxide was used 
directly from a cylinder. 
The results obtained by E. Rutherford! for the sum of the velocities of the ions 
produced by Rontgen rays are for : — 
Air = 3‘2 centims. per second. 
Oxygen = 2 - 8 centims. per second. 
Carbonic acid = 2T5 centims. per second. 
Hydrogen = 10'4 centims. per second. 
It is not stated whether the gases were dried, but the value for air agrees with 
that given above for the sum of the velocities in dry air, while the values for oxygen 
and hydrogen agree with the values for the moist gases. The value for carbonic acid 
is nearly 40 per cent, larger than that obtained here. It is of interest to compare 
the velocities of the ions produced by Rontgen rays with those of the ions produced 
by the action of ultra-violet light and in the discharge from points, as they show a 
close similarity. 
For conduction produced by ultra-violet light, E. Rutherford| obtained with 
dry gases for the velocity of the negative ions in—- 
Air = 1 ’4 centims. per second. 
Hydrogen = 3 *9 centims. per second. 
Carbonic acid = '78 centim. per second. 
The value for carbonic acid is quite near to that obtained above, but the other two 
are considerably smaller. 
A. P. Chattock§ obtained for the velocities of the ions in dry air in the case of 
discharge from points— 
413 centims. per second for the positive ions, and 
540 ,, ,, ,, negative ions for a field of one electrostatic unit. 
* J. Zeleny, ‘Phil. Mag./ July, 1898. 
t E. Rutherford, ‘Phil. Mag.,’ November, 1897. 
X E. Rutherford, ‘Proc. Camb. Phil. Soc.,’ vol. 9, Pt. VIII. 
§ A. P. Chattock, ‘ Phil. Mag./ November, 1899. 
