420 Prof. J. C. McLennan and Mr. C. L. Treleaven 



on 



from dilute sulphuric acid acting on granulated zinc. It, 

 too, was carefully dried, but it is probable that it contained 

 some air. The methyl iodide was introduced by evaporation 

 into the electrometer by placing a small bottle of it with cork 

 removed in the small chamber attached to the instrument, 



Table I. 



Ionization op Gases. 



Gas. 



q = no. of ions generated per c.c. per second. 



Air .. 



Hydrogen '.. 



Bow land. 



London. 



Toronto. 



Atlantic Ocean. 



8-62 



318 



24-57 



8-73 



8-8 

 2-0 



4-65 

 1-8 



Acetylene 



5 







Methyl iodide 1 

 and air J 



14-81 



— 



— 



which usually contained the metallic sodium. The instru- 

 ment was filled with air when this was done, and the 

 pressure of the methyl-iodide vapour was probably about 

 one-half a centimetre of mercury. 



These readings served to bring out the fact that the 

 ionization in air on the ocean was about one-half what it 

 was on land ; that with methyl-iodide vapour in air the 

 ionization in the latter was nearly doubled ; that the 

 ionization in hydrogen was very low and was about the same 

 on land as on water ; and that the so-called natural ioniza- 

 tion of acetylene was extremely high. With the tube S S 

 down, the loss of charge from the charged electrical system 

 was about the same with acetylene as with air, which showed 

 that the high value obtained for u q" with acetylene was not 

 due to any loss of charge over the supports arising from any 

 action of the gas on the pieces of amber which carried the 

 fibres. 



IV. Second Investigation. 



In the second investigation the readings were taken with 

 a number of different gases — first, in a room free from radio- 

 active contamination in the Physical Laboratory at Toronto, 

 and then out on the ice on Lake Ontario at a point about 

 halt a mile from the shore where the water was about 20 feet 

 deep. The temperature in the laboratory when the readings- 



