2 DISTRIBUTION OF THE ACTIVE DEPOSIT OF 



Practicallj^ all the testiag vessels used in the above re- 

 searches were cylindrical cases having an insulated rod in 

 the centre. These vessels have the disadvantages of having an 

 ununiforni field and of presenting surfaces of unequal area to 

 the active deposits. Therefore it was decided to try vessels 

 having parallel plate electrodes. It is important that the 

 testing vessel be so constructed that the active deposit 

 particles or "rest atoms" would be deposited only on the elec- 

 trodes and none on other parts of the vessel where they would 

 remain unmeasured. To accomplish this several types of 

 vessels were used, onlj^ two of which need be described. The 

 construction of the first type is shown in Figs. 1 and 2. The 

 electrodes were cut out of zinc as shown in Fig. 1. The flaps 









-JT 









ID 



^IZ5> 

















1 



























1 



1 



J 

 1 



h- - 



Vcm ^ -*^ 



1 





Fig. 1. 



