424 Prof. J. C. McLennan and Mr. C. L. Treleaven on 



the ice of the lake. In Table III. the ionization in the 

 various gases under the different conditions is expressed 

 on the basis of 100 for air. 



Table III. 



Ionization ratios 

 On basis of air = 100. 



Gas. 



Column 1. 



Alpha 

 rays. 



Column 2. 1 Column 3. 



Column 4. 



Column 5. 



Column 6. 



Drop in 



ionization. 



Beta 



rays. 



Gramma 

 rays. 



Natural 

 ionization in 

 laboratory. 



Eesidual 



ionization on 



ice of lake. 



Air 



100-0 

 80-4 

 56-0 



113-3 

 77-6 



1169 



100-0 

 1560 

 15 9 

 149-5 

 150-5 

 130-2 



100-0 

 157-0 

 158 

 1480 

 154-8 

 134-2 



1000 

 114-3 

 226 

 139-7 

 123-6 

 3221 



ioo-o 



110-3 

 25-3 

 144-3 

 114-6 

 616-4 



1000 

 118-0 



200 

 135-0 

 132-7 



21-0 



Carbon dioxide... 



Ethylene 



Nitrous oxide . . . 





From this table it will be seen that the numbers repre- 

 senting the ionization for all the gases are about the same 

 for beta as for gamma rays. For alpha rays the relative 

 ionization in hydrogen was much greater than it was for 

 either beta or gamma rays, while in carbon dioxide, ethy- 

 lene, nitrons oxide, and acetylene, it was considerably less. 

 Under the heading ''Natural ionization/'' it will be seen that 

 the readings for acetylene were very high, namely, 27*9 on 

 land and 27*0 on the ice. The reading 27*9 was the mean of 

 a number of readings all about the same, taken with acety- 

 lene in the laboratory, but the reading " q " = 27 for acetylene 

 on the ice was the only one taken. This reading was taken 

 in a hurry and it was the intention of the writers to repeat 

 it, but the opportunity for doing so did not come before the 

 ice on the lake had melted in the spring. The difference in 

 the two readings, it will be seen, is only 0'9 ion per c.c. per 

 second, which is only about one-fourth or one-fifth of what 

 one would have expected to get, judging by the results 

 obtained with the other gases. 



The numbers given in the fifth column of Tables II. and 

 III. represent the residual ionization in the different gases 

 on the ice. With the exception of that for acetylene, the 

 numbers approximate to those given in the sixth column for 



