﻿S78 



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



for the positive carriers it decreases it only to \. This is 

 because the free electrons, which form the greater part of the 

 negative carriers, become rapidly loaded with air molecules, 

 and pass upwards with the current of air. For this, among 

 many reasons, the velocity of the electrons cannot be estimated 

 by this method, In fig, 6 are given curves for both positive 



Current — »■ 



and negative, made for two different distances of the electrode 

 and strip from the flame, the smaller distance being 0*8 cm., 

 the greater 1*8 cm. Positive and negative readings were 

 taken alternately by changing the sign of the electrode. 



With Sr, as before mentioned, metal was not detected on 

 the strip, when the electrode was negatively charged. With 

 Na, however, the colour was unmistakably obtained with a 

 run of a few minutes, though not nearly as bright as when 

 the insulated electrode was positive for the same time. 



The controls before enumerated rendered it certain that 

 there really was a transport of metal on the negative side, 

 though far less than on the positive side. This, together 

 with the fact that about a thousand times as much Sr as Na 

 is necessary to give a perceptible colour in the flame, would 

 account for the Sr not being detected on the negative side. 

 The presence of these metallic negative carriers enables us to 

 explain the decrease of current which takes place on the 

 negative side on introducing the bead if the strip is hori- 

 zontally in the neighbourhood of the bead ; this decrease is 

 plainly shown in figs. 5 and 6. We assume that some of the 



