Section III., 1904 [ 6S ] Trans. R. S. C. 



IX. — On the Radioactivitij of Natural Gas. 



By Dr. J. C. McLexxan, of the University of Toronto. 

 (Read June 22, 1904.) 



Tn a paper by Mr. E. F. Burton, B.A., recently published in the 

 V^iiversity of Toronto Studies, I'liysical Science Series, an account is 

 given of some experiments with a highly radioactive gas obtained from 

 crude petroleum. In this investigation it was found that air drawn 

 through crude petroleum became charged with a radioactive emanation, 

 which, from the rate at which its activity decayed and from the nature 

 of the induced radioactivity which it produced, the author concluded to 

 be an em'anation from radium. 



The present writer has extended this investigation to an examina- 

 tion of the natural gas from different wells in Western Ontario. The 

 gas from every well examined, which included those in the Welland 

 district as well as those near Brantford, was found to be charged with 

 ,a radioactive emanation. The activity of this emanation was found 

 to decay or die out in all gases to one-half its original intensity in 

 about three days, and the intensity of the induced radioactivity which 

 it produced died down to one-half value in about 40 minutes. 



The wells examined varied in their depths, and the amount of 

 active emanation present was found to be practically the same in all 

 wells coming from the same horizon. In the Welland district the gas 

 from those wells which had their source in the ]Sriagara formation 

 possessed the highest initial conductivity. On an arbitrary scale this 

 conductivity is represented by about 1,200. The gas of those wells 

 which had their source in the Clinton limestone possessed an initial 

 conductivity of about 145, while that from the wells coming from the 

 Medina formation gave an initial conductivity of about 680. One well of 

 this group, which had its source in the Trenton limestone, and had a 

 depth of about 3,000 feet, gave Ijut a feeble conductivity of not more 

 than about 147. The highest conductivity obtained in the investigation 

 was that of the gas from a well near Brantford. The conductivity in 

 this case was about 9.000. An investigation of this gas showed that, in 

 virtue of the emanation with Avhich it was charged, there was produced 

 about 15,000 ions per second in each cubic cm. of its mass. A test 

 made on the conductivity of ordinary atmospheric air in the same way 

 showed a production of al'out 33 ions per cubic cm. per second. This 

 comparison will give an idea of the extrjiordinary amount of the radio- 

 active emanation present in some of our natural gases. 



