Radium present in Typical Rocks of Montreal. 231 



The amount of energy transformed per cubic centimetre of 

 a metal into radiant energy per second is surprisingly large : 

 nearly the whole of this is absorbed by the metal, and passes 

 into a form other than that of radiant energy. We have 

 seen that if E is the radiant energy per unit volume in 

 the body when in the steady state, the amount of radiant 

 energy produced in a cubic centimetre of the substance 

 per second is 



C . 4t t V 2 . E 

 K 



Now YE is the stream of radiant energy passing through 

 the substance ; by Stefan's law it is equal to aO 4 at the 

 absolute temperature 6, and o* is about 10" gram calorie. 

 For silver c, the specific conductivity, is about 1/2000 ; hence 

 at the temperature 27° C. or 300 absolute the radiant energy 

 produced per cubic centimetre of the silver per second is 

 equal to 



^ . 10" 5 X (300) 4 or £ 1-5 x 10 6 calories. 



Thus if K were unity the radiant energy produced in a 

 cubic centimetre of silver represents about 8000 horse- 

 power. Thus, though a cubic centimetre of silver does not 

 distribute its radiant energy well, it produces as much as a 

 good-sized electric-lighting station. 



XVIII. The Amount of Radium present in Typical Rocks in 

 the immediate Neighbourhood of Montreal. By A. S. Eve, 

 M.A., and D. McIntosh, D.Sc* 



IN 1906 Strutt made a careful and thorough investigation 

 of the amount of radium present in specimens of rocks 

 obtained from sources differing widely in geographical dis- 

 tribution and in geological time. His results, published in 

 the Proceedings of the Royal Society (May 14th and 

 August 18th) were most remarkable and important ; and it 

 may be convenient to reprint them in the present communica- 

 tion. But it is necessary to apply a correction depending 

 on the ratio of radium associated with uranium, which in the 

 results first published was not correctly assumed, because 

 the value ultimately found by Rutherford and Boltwood was 



* Communicated to the Royal Society of Canada. Communicated by 

 the Authors. 



