44 



THE ROYAL SOCIETY OF CANADA 



was found on doing this that practically no current passed through 

 the liquid air. A small plate of copper about 1 sq. cm. in area having 

 on it a deposit of poloniiuii which had previously been washed in water 

 and dried was then attached to the face of the electrode B with the 

 polonium facing the electrode A. A second series of readings was then 

 taken with increasing potentials applied to EA. After this the copper 

 plate carrying the polonium deposit was quickly removed and a thhd 

 set of readings taken without it. A slight conductivity was generally 

 obtained in this third set of readings lout its amount was found to depend 

 very largeh^ upon the time which was allowed to pass in taking the second 

 and third sets of readings. 



In the intervals between the first and second sets o^ readings and 

 the second and third sets, care was taken to see that the deposit ot 

 snow and ice crystals was lemoved from the glass and quaitz tubes 

 surrounding the wires leading to the electrodes. These tubes, the lead- 

 ing wires and the electrodes were also thoroughly dried before they 

 were inserted in the liquid air for the second as well as for the third 

 sets of readings, in order to make certain that no moisture was intro- 

 duced with them into the liquid air. All possible care was taken to 

 prevent ice crystals falling from the wires into the liquid air during 

 the course of the measurements. But it was difficult to make certain 

 that moisture did not deposit from the air upon the surface of the liquid 

 air, and the small conductivity generally observed in the third set of 

 readings was taken as an indication that such deposition was not 

 entirely prevented. 



TABLE IL 

 Conductivity imparted to Liquid Air l)y Alpha Rays from Polonium. 



The readings given in Table II and the curve representing them in 

 Fig. 2 will serve to illustrate the variation obtained, with different 



