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THE ROYAL SOCIETY OF CANADA 



1 .008, and it is evident that the loss in energy is of a very small order 

 being 1 in 460 or 0.216 per cent. If this theory could be applied to 

 heavy atoms such as lead (207) and silver (108), then the loss in 

 energy is seen to be almost non-existent, actually for lead 0.00105 per 

 cent. 



This analysis is based on the assumption that the collision is of 

 the nature of the passage of a comet around a large star, that is to say, 

 considerations of energy-loss due to radiation, and of alteration of 

 mass with velocity are neglected. These points would require special 

 treatment. It is true that, unlike the case of the a-particle, a large 

 deflection of a ^S-particle may sometimes be the result of many col- 

 lisions whereby the electron has been buffeted about in an erratic 

 manner for possibly a considerable time before it finally emerged in 

 the direction from which it entered. But on the above theory it 

 would require 10,000 collisions with lead atoms to produce a 10 per 

 cent, loss in energy. 



It is, therefore, concluded that the loss in energy is certainly 

 much less than 10 per cent, and is possibly zero. 



This is a point of considerable theoretical importance, as it indi- 

 cates that the phenomenon of the scattering of j8-rays does not 

 furnish an explanation of the production or excitation of 7- or X-rays. 



Part II 



The complex jS-rays emitted from a source like Ra.E can be 

 represented by a Velocity Distribution Curve of the type of the Max- 



wellian Probability curves. 

 There will be a minimum 

 velocity vo (see Fig. 6) near 

 the origin below which /3- 

 rays do not ionize and 

 hence are not detectable as 

 /3-rays. The curve will 

 begin at this point, rise to 

 its maximum over v, where 

 V is the most probable vel- 

 ocity, and then fall to a 

 point just short of c where 

 c is the velocity of light. 

 The presence of an absorb- 

 ing plate in the path of the 

 rays causes a two-fold change : (1) in the shape of the curve, v approach 

 ing Va as the velocity of the transmitted rays is decreased; (2) in the 



