on the Ions produced in Air by Rontgen Rays. 



439 



The following table contains a summary of the above 

 results : — 



* 



X. 



v v 



v 2 . 



m. 



e. 



0-45 



133 



1-9x10-2 



2-62x10-2 



81x10-12 



2-3x10-10 



100 



+6-7 





4-36 



25 



2-6 



0-50 



133 



4-39 „ 



5-3 



28-6 „ 



4-4 



050 



13-3 



2-68 „ 



3-41 



136 „ 



2-7 



0-50 



133 



34 „ 



4-2 



19-5 „ 



3-4 



0-55 



121 



3-27 „ 



411 „ 



18-3 „ 



3-8 



0-40 



167 



1-9 „ 



3-4 



8-1 „ 



3-8 



0-40 



167 



1-93 „ 



31 



8-3 „ 



30 



040 



16-7 



1-98 „ 



3-34 „ 



8-6 „ 



3-5 



0-40 



125 



1-26 „ 



2-00 „ 



4-4 „ 



2-0 



0-44 



152 



193 „ 



2-72 „ 



8-3 „ 



2-3 



Mean .. 



...3.1+10-10 



It will now be convenient to consider the less numerous 

 sets of droplets which fell quicker than the principal set on 

 which the above observations were made. 



When no field was applied the whole cloud fell at the same 

 rate and its upper surface was sharp. No sign of any sepa- 

 ration into sets could be detected. When the field was applied 

 the cloud fell quicker than before, but otherwise its appear- 

 ance was at first the same. After a few seconds, however, 

 the surface of the cloud began to separate into two ; appa- 

 rently some of the cloud falling quicker than the rest. The 

 line of separation between the two sets was fairly sharp. 

 Sometimes three such sets were observed. 



The following numbers were obtained in one series of 

 experiments with the disks 0*4 cm. apart : — 



x=o. 



X=+12-5. 

 Principal set. 



X= 4-12-5. 

 Second set. 



X= 4-12-5 



First set. 



sees. 



sees. 



sees. 



sees. 



336 



200 



15-4 



11-0 



33-0 



200 



15-0 



106 



30-5 



20-0 



140 



100 



31-6 



20-4 





108 



29-4 







104 



Mean 31-62 



Mean 20-1 



Mean 148 



Mean 1056 



^=0-0126 



i'„ =0-020 



:0'027 



: 0-038 



We might suppose that the subsidiary sets are produced 

 by two droplets coalescing under the influence of the field, 

 but it is easy to show by calculation, that a droplet with twice 

 the mass and twice the charge of the others 



charge 

 2 G2 



ought to have 



