122 THE ROYAL SOCIETY OF CANADA 



The values recorded represent the number of ions generated per 

 c.c. per second in the ionisation chamber of the electrometer under 

 the different conditions mentioned assuming the ionic charge to be 

 4-65 X 10-^° e.s.u. Under the heading of "alpha rays" "beta rays" 

 and "gamma rays" the numbers represent the increases in the value 

 of q for the different gases when traversed by the respective types 

 of rays. 



The final column headed "Drop in Ionisation" contains numbers 

 representing the difïerences in the values obtained for "q" under 

 natural ionisation in the Laboratory and on the ice of the Lake. 

 In Table III the ionisation in the various gases under the different 

 conditions are expressed on the basis of 100 for air. 



From this table it will be seen that the numbers representing 

 the ionisation for all the gases are about the same for beta as for 

 gamma rays. For alpha rays the relative ionisation in hydrogen 

 was much greater than it was for either beta or gamma rays while 

 in carbon dioxide, ethylene, nitrous oxide and acetylene, it was con- 

 siderably less. Under the heading natural ionisation 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 acetylene 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 ions per c.c. per second which is 

 only about one fourth or one fifth of what one should 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 repre- 

 sent the residual ionisation 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 the respective gases, i.e., the drops in 

 ionisation and the residual ionisation for these gases are about in the 

 same ratio. As the drops in ionisation are due to the absence of the 

 earth's penetrating radiation which is probably of the gamma type 

 one should have expected the numbers in column 6 to be approxi- 

 mately the same as those in Column 3 (or Column 2 since the ionisation 

 under gamma rays is very probably due to secondary beta rays 

 emitted by the walls of the electrometer). The differences, however, 

 are considerable which would point to the probability of the earth's 

 penetrating radiation being somewhat different in quality from the 

 gamma rays used in obtaining the numbers given in Column 3. 



