320 



Mr Aston, Distribution of intensity 



hit the central spot but may result in it splitting into two atoms 

 one with a positive one with a negative charge. The energy of 

 impact may be itself capable of causing this, if not some other 

 cause, e.g. radiation, may effect the dissociation. In any case it 

 would give exactly the observed result, i.e. two bright patches 

 lying symmetrically on the extension of the line joining the 

 primary spot to the origin at twice its distance from the latter, 

 corresponding to half the mass but the same velocity. 



Fig. 2. Molecular Tyi^e. 



The general appearance on the screen when both types of 

 discharge are present is indicated in Fig. 3. 



Effect of different forms of cathode. 



Experiments were performed with plane, concave and convex 

 cathodes. Convex cathodes are the least efficient in producing 

 bright effects but give the molecular type with the least atomic 

 blurring. Concave ones are most efficient and throw the maximum 

 energy into the atomic type which can be obtained practically 

 pure with them under a moderate range of conditions. The original 



