50 



THE ROYAL SOCIETY OF CANADA 



A - Ctiancoal Tubes 



B - Mencury Seals 



G ~ Mercury Traps 



D " Mercury Manometer 



E: - Gdd-leaf niter 



Figure 2. — Central Portion of Flow Apparatus. 



to preclude the possibility of air leaks at taps. These seals were 

 operated by lowering or raising the mercury reservoirs according as 

 it was desired to open or close a path to the gas flow. 



For use the whole apparatus was first exhausted; the charcoal 

 tubes were surrounded by liquid air and gas was allowed to stream 

 slowly in until atmospheric pressure was attained. When ^ steady 

 condition was obtained, a flow of gas was started, and continued so 

 long as the purity meter read above 99-8%. When this percentage 

 began to fall the gas stream was diverted through the second set of 

 tubes and the purification continued. Meanwhile the charcoal in 



