[EVE & M’INTOSH] RADIUM IN ROCKS NEAR MONTREAL LE 
an accurate determination with the least expenditure of time and 
chemicals. 
In conclusion, it must be remembered that in the calculation of 
the amount of radium necessary to maintain the earth’s temperature 
gradient no allowance has been made for the heating effects due to 
thorium, uranium and actinium. ‘There is evidence that thorium 
must be widely distributed in the earth, as the active deposits of thorium 
have been found in the atmosphere in most places where an attempt to 
discover them has been made. 
We are indebted to Professor Rutherford for his interest and advice 
in this work, and to Professor Adams and Mr. Bancroft for their assis- 
tance in matters geological. 
Sec. IIT., 1907. 2. 
