880 Prof. J. S. Townsend and Mr. V. A. Bailey on 



W in centimetres per second. 

 Z in volts per centimetre. 

 p in millimetres of mercury. 



Table I. — Nitrogen. 



p. 



Z. 



Z/p. 



*. 



Wxio- 5 . 



20 

 10 



8-5 

 4-25 



0425 

 0-425 



11-5 



10-4 



5-85 

 5-9 



20 



10 



5 



16-9 



8-5 

 4-25 



0-845 



0-85 



0-85 



18-9 

 19-1 

 18 5 



7-77 

 7*56 



20 

 10 



5 



2-5 



10 

 5 

 2-5 



33 4 

 16-9 

 8-35 

 4-25 



1 -67 

 1-69 

 1-67 

 170 



28-2 

 27-S 

 290 

 28 3 



111 

 ll'l 



337 

 16-9 



8-4 



3-37 

 338 

 336 



36-1 

 37-0 



35-8 



19-6 

 19-7 

 19-1 



5 



2-48 



1-25 



2-48 

 1-25 

 0-62 



33-7 

 168 



8-4 



6-74 

 6 79 

 6-73 



449 



449 

 44-1 



35-6 

 35-1 

 32-2 



33-8 



16-8 



8-5 



13-6 

 13-4 

 13-7 



51'3 

 520 

 530 



624 

 625 



1-26 



0-622 



33-9 

 16-9 



269 

 27-1 



66-8 

 68-8 



no 



105 



0-625 

 0-303 



i 



33-9 

 16-8 



54-3 



55-6 



117 

 121 



181 



of tliem formed ions in passing from the plate A to the 

 plate B in the apparatus shown in fig. 1. double this number 

 would be formed if the electrons moved for the same 

 distance through the gas at pressure 2p under a force 2Z. 

 Thus, in an apparatus of fixed dimensions the greater the 

 pressure of the gas the greater the number of ions that would 

 be formed. 



The state in which the proportion of ions to electrons in a 

 <ias is increasing with p is thus easily recognized by the 

 fact that W and h cannot be represented in terms of the 

 ratio Z/p alone. 



If the ions which are formed are not stable, as is the case 

 when the electron may be dissociated by collisions from the 

 molecule or group of molecules which the ion comprises, 



