Currents to the Study of Ionization by Collision. 463 



platinum wire is tied on to a silk thread, the upper end of 

 which is wrapped round a groove cut in the plug of the stop- 

 cock F which serves as a windlass for raising or lowering the 



Fig. 1. 



r V 



plate A. The platinum tube E is connected to a platinum 

 wire sealed through the wall of the glass tube at 0. The 



2L2 



