22 Larmor, Physical Aspect of the Atomic Theory. 



as among the tones that belong to a bell the particular 

 ones that ring out from it depend on the mode in which 

 it is struck. The increased translatory motion at higher 

 temperatures can hardly make a difference in the 

 vibration ; there remains the increased spinning motion 

 accompanying it, which at first sight offers some promise. 

 It might even be asked whether, in the dissociative equili- 

 brium which arises in some gases at high temperatures, it 

 may not be just as likely that the atoms should slip apart 

 gradually as the result of the increased whirling motion 

 of the molecule at the higher temperature, as that they 

 are broken apart at the time of collision. But if ultimate 

 separation can thus gradually arise, the earlier stage of 

 merely modified configuration would change the periods 

 of the spectral lines or bands of the molecules in which 

 it occurs, and if there were enough of them, it would show 

 as a widening of the lines of the spectrum. Thus, what- 

 ever may be the case for the far smaller numbers of 

 degrading radio-active molecules, for ordinary gases no 

 way is open in this direction : the change must be abrupt, 

 and the manner in which the molecule is struck, the nature 

 of the collision, must somehow supply the cause of the 

 variation in the intensity of the lines. Or it may be that 

 the dissociation which accompanies the production of a 

 line-spectrum takes place in successive transient stages 

 (of. p. 30) and that the durations of these stages have an 

 influence on the relative brightness of the lines. 



Electric PJienomena. 



A survey of the general features of the atomic theory 

 would be far from adequate which omitted the fun- 

 damental atomic properties announced by Faraday in 

 1834 in following the path opened up by Davy's electro- 

 chemical work, and carefully formulated by him under 



