﻿866 Dr. E. N. da C. Andrade on the Carriers of 



times as great as that o£ Lenard, e. g. for lithium he finds 



63 



cm. /volt , t , n ~ cm. /volt -^ jT . 



/ and Lenard OOb / . fcrom this 



sec./ cm. sec./ cm. 



Lenard (loc. cit. p. 647) infers the probability of the existence 

 of two kinds of positive carriers, but there appears to have 

 been no attempt made to demonstrate this with certainty, or 

 to explain the discrepancy. 



It seemed to me desirable to establish clearly the simul- 

 taneous existence of, and distinguish the difference between, 

 the two kinds of positive carriers, and especially to show the 

 existence of both kinds with a common method. The 

 arrangement adopted was similar to that used by Lenard for 

 deflecting the coloured streak, the electrodes being vertical 

 and outside the flame : the Wilson carriers, which are 

 invisible, are then driven sideways out of the flame, and 

 detected as described later. Their velocity has been 

 measured, and found to be smaller than that given by 

 Wilson ; experimental and theoretical grounds are brought 

 forward for supposing that Wilson and subsequent experi- 

 menters using his method have made an erroneous assumption 

 as to the origin of these carriers, which makes the velocity 

 work out too hi«h. 



It has been shown in the course of the work to be described 

 that the faster positive carriers are metallic, like the slower 

 ones, probably metal atoms, thus contradicting the theory 

 that the positive carriers in flames are hydrogen. Expe- 

 riments have also been made on the negative carriers, 

 showing, among other things, that metallic negative carriers 

 exist. 



For convenience the slower positive carriers which form 

 the luminous streak, whose velocity was measured by Lenard, 

 a\ ill often in the following be called u carriers of the first 

 kind " ; the faster carriers, not seen as luminous, measured 

 by Wilson, " carriers of the second kind." 



A critique of previous work on the subject will be found 

 at the end of the paper. 



§ 2. Method and Apparatus. 



The essence of the method is as follows : the flame is 

 placed between two plate electrodes, one earthed, and the 

 other insulated and connected with an electric machine ; the 

 fast moving positive carriers are in this way driven sideways 

 out of the flame, and some of them fall upon an insulated 

 platinum strip, which is connected to earth through a high 

 resistance galvanometer, and is fixed close to the earthed 



