SECTION III., 1907. [13 ]} Trans. R. S. C. 
III—The Amount of Radium Present in Typical Rocks in the Im- 
mediate Neighbourhood of Montreal. 
By A. S. Eve, M.A., anp' D. McIntosH, D.Sc. 
(Communicated by Professor E. Rutherford, and read May 15, 1907). 
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 distribution and in geological time. 
His results, published in the Proceedings of the Royal Society, (May 
14th and August 18th), were important and remarkable. He found 
that the amount of radium in the rocks near the earth’s surface was 
greatly in excess of that required to maintain the earth at its pre- 
sent temperature. Professor Rutherford has calculated that the 
heat from 0.05X10—1? gram of radium in every gram of the 
earth would be sufficient to compensate for the loss of heat from the 
earth by conduction and radiation. If we apply a correction for the 
ratio of radium associated with uranium, which in the published results 
was not correctly assumed, we find that the following averages may be 
obtained from Strutt’s determinations :— 
Igneous rocks, 1.7><10~'? gram of radium, per gram of rock. 
Sedimentary rocks, 1.1X10-1°* gram of radium, per gram of rock. 
Mean value, 14X10—1? gram of radium, per gram of rock. 
Hence it appears that near the earth’s surface there is about 28 
times as much radium present as will account for the existing known 
temperature gradient within the earth. This result is so unexpected 
that it seems desirable to check all available data before embarking 
on speculative hypotheses. Moreover, Strutt, in his work, ignored 
the twin continents of North and South America, for he did not select 
a single specimen for investigation from the New World. 
For these reasons the present writers decided to examine repre- 
sentative rocks obtained in the immediate neighbourhood of Montreal. 
Professor F. D. Adams kindly recommended a typical series, and 
his assistant, Mr. Bancroft, was good enough to procure specimens from 
the field. 
Three igneous rocks were selected: Essexite, which forms the main 
mass of Mount Royal, Nepheline Syenite, and the intrusive dyke, 
Tinguaite. All these were thrust through the Ordovician plain in 
