546 Lucian — Distribution of the Active Deposit of 



respect to the central electrode, three out of four outlet tubes 

 being stopped. 



The effect of the irregularities of the field was examined in 

 a separate series of experiments. The variation of the electric 

 intensity in the cylindrical portion of the vessel and in the bot- 

 tom will not obey the same law, no matter what the construc- 

 tion of the bottom is. As a consequence, we would expect to 

 find discrepancies in the relative number of the neutral par- 

 ticles formed in the body of the vessel and near the bottom, 

 and diffusing to the electrodes. The bottom corner of the 

 vessel was tilled in with a curved piece to get rid of the edge 

 effect, and gauze bottoms of various shapes, flat and curved, 

 tried. It was then found that, although discrepancies in the 

 values of the cathode percentage for different shaped gauzes 

 occurred, these never exceeded the limits of experimental 

 error, and did not exhibit any consistent direction, as one would 

 be led to expect from the consideration of the different shapes 

 of the bottoms. Evidently the high velocity of the air stream 

 helped to smooth out the irregularities that would be expected 

 at lower pressures. Finally the curved gauze, shown in the 

 diagram, was adopted in order to match up with the curvature 

 of the corners. It will be noticed that the distance of the 

 electrode from the gauze is adjusted so that the average elec- 

 tric intensity at the bottom of the vessel would not by any 

 chance be smaller than in the body of the vessel. 



III. Experimental Results. 



Before giving the experimental results of this investigation 

 it may be useful to recapitulate the transformations which a 

 quantity of emanation undergoes, according to our present 

 state of knowledge. 



The complete scheme of transformation, after Marsden and 

 Perkins,* is as follows : — 



ft 



a(5.7cm S .) a(es) 



3.S 5CCS. 



ACTIVE DEPOSIT 



oo 5 sees 



*E. Marsden and Dr. P. B. Perkins, Phil. Mag., vol. xxvii, Apr., 1913. 



