Behaviour of Metallic Vapours in Flames. 



35 



far as the negative electrode, which would make the current 

 too great. The number need not be large, since the mutual 

 action between metal atoms and the glowing electrode is so 

 great (§ 3). 



Fig. 6. 



/°/f TSSi/ffS -*■ 



ff?£S3Uf?£ ■ 



§ 11. Theoretical. 



The general result of measurements extending over a 

 range of pressure of 0*4 to 4 atmospheres is that the velocity 

 of migration of positive metallic carriers of the first kind is 

 inversely as the pressure. Now, according to all formulae 

 for the mobility of a charged atom in a gas *, the mobility 

 is inversely as the pressure of the gas. Hence we conclude 

 that the fraction of time during which a metallic carrier is 

 positively charged is independent of the pressure. 



This leads us to the conclusion that the liberation of the 

 electron from the metallic atom is, mainly at least, effected 

 by the impact, or rather, perhaps, the action at short distance 

 (Nahewirkung) of metal atom on metal atom. For the 

 number of these impacts remains constant with varying 



* E.g. the formula given by Lenard (A?m. der Phgsik (4) iii. p. 313 

 (1900)) for the mobility of a charged carrier of atomic size, 



3 eF 



2W2 WW 

 where s is the sum of radii of carrier and gas molecule, 



D is the density of the gas, 

 W is the mean velocity of the gas molecule. 



D2 



