﻿THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[SIXTH SER 



^ 



JUNE \&Wi?''Z J&fa 



'•■V 'i 



LXXXVII. On the Nature and Velocity of Migration^of 

 the Carriers of Electricity in Flames containing Metallic 

 Vapours. By E. N. da C. Andrade, B.Sc, Ph.D., 1851 

 Exhibition Scholar of University College, London *. 



§ 1. Introduction. 



rpiHE experiments here described, which were carried out 

 JL in the Radiologisches Institut of the University of 

 Heidelberg, are primarily concerned with the velocity of mi- 

 gration and origin of the positive carriers of electricity which 

 are formed when a metallic salt is brought into the Bunsen 

 flame. Lenard t has shown that if a bead of a salt of one of the 

 alkali metals be brought into the Bunsen flame, the coloured 

 streak so formed is deviated in an electric field, and behaves as 

 if positively charged. He estimates the velocity of migration 

 of the carriers in unit field from the inclination of the luminous 

 streak, and the upward velocity of the flame. Previously to 

 Lenard's paper H. A. Wilson $, using two horizontal elec- 

 trodes in the flame itself, had measured the velocity of the 

 positive carriers by driving them down against the current 

 of the flame gases : he estimates the field required to bring 

 them to the lower electrode by the current between the 

 electrodes. The value obtained by Wilson is about 1000 



* Communicated b^y Prof. Sir J. J. Thomson. 



t P. Lenard, Ann. dor Plujsik (4) ix. p. 642 (1902). 



1 II. A. Wilson, Phil. Trans. A. cxcii. p. 409 (1899). 



Phil Mag. S. 6. Vol. 23. No. 138. June 19.12. 3 L 



