Active Deposit of Actinium in an Electric Field. 773 



entirely to neutral particles ; for, if negative particles ex- 

 isted in the vessel, the activity when the central electrode is 

 made the anode should be larger than the amount which 

 settles there by diffusion alone ; whereas by a simple calcula- 

 tion, from the value of diffusion on the case, we find that for 

 -+■ 600 volts on the case and a total amount corresponding to 

 10*78 mm ./sec. the activity diffusing to the central electrode 

 is *113, which is larger than the value obtained here (*08) 

 for —600 volts on the case. This shows conclusively that 

 no negative particles exist, or at least, take part in the 

 transfer of activity considered. 



The above difference between the values of the active 



Fig. 3. 



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deposit that diffuses to the central electrode as anode and 

 cathode can be explained by considering the different relative 

 distribution of charged deposit particles and negative ions, 

 the different conditions of electric intensity and the consequent 

 different amount of recombination near the central electrode 

 and in the neighbourhood of the boundary of the vessel. 



The curves shown in fig. 3 are plotted from those in fig. 2 

 by taking the points in which the curves of fig. 2 intersect a 

 vertical line, corresponding to a given amount of emanation. 



The earlier portions of the curves show clearly the increase 

 of volume recombination with the increase of the amount of 

 •emanation employed. The gradual rise of the curves after 



