Ionization produced in Gases by Rontgen Rays. 93. 
Measurements on Carbon Dioxide and Hydrogen. 
The next gas experimented upon was carbon dioxide. It 
was treated in exactly the same manner as air had been. It 
was prepared in the ordinary way by the action of pure 
hydrochloric acid on marble, and was dried by passing it 
over pumice-stone moistened with strong sulphuric acid 
before it entered the cylinder. The results obtained with 
this gas were quite in accordance with those obtained for air. 
Observations were taken over an even greater range of 
temperatures than in the case of air, and the same law was 
found to hold with the carbon dioxide as was shown to hold 
in air. A series of results for this gas is shown in Table IIT. 
TaBLE IJ].—Carbon Dioxide. 
lonization as represented 
by Scale-Divisions for Ionization as represented | Temperature of 




ees Jerse) pe ney emily | OyEnds 7 A. 
80°1 24-9 222° C. 
84-4 | 25:1 Te gee 
89-0 | 25-2 146° 
79-1 ) 24-6 ) 108° 
83-8 | 26:2 | 69° 
87+] | 253 | aio 
A considerable number of experiments were also made on 
hydrogen. It was found very difficult to obtain really 
satisfactory results with hydrogen on account of the great 
dithiculty experienced in making the cylinder perfectly gas- 
tight for this gas. The joints which proved so satisfactory in 
the case of air and carbon dioxide gas did not serve the 
purpose so well in the case of hydrogen, on account of the 
greater ease with which it diffuses, and I was consequently 
never able to make the vessel perfectly g gas-tight for hydrogen. 
The difficulty was also increased by the fact that the amount 
of ionization produced in hydrogen is so much smaller than 
in the other gas, and therefore the effect to be measured was 
much smaller. Consequently the results obtained for hydrogen 
were not so accurate as those obtained in the case of air and 
carbon dioxide. However, taking the results as a whole, 1 
think we may conclude that the same law holds for hydrogen 
as holds in other cases. Table IV. contains a set of results 
obtained for hydrogen. 
