1904.] 



certain Minerals and Mineral Waters. 



193 



concentrated material was kept until, by lapse of time, it had become 

 weak enough to be conveniently used. Its activity was followed until 

 it had become too small for measurement. 



With this preface the results for the various minerals tried may be 

 given in the form of a table. The rates of leak are given in scale 

 divisions per hour. When air alone filled the apparatus, the rate of 

 leak was 2*25 sc. div. per hour. This was in each case subtracted. 



Mineral. 



Locality. 



Quantity 

 taken in 

 grammes. 



Rate of 

 leak 



due to 

 emanation 



(sc. div. 

 per hour). 



_K>ate oi 

 leak per 



100 

 grammes. 



Time in 

 days taken 



by tbe 

 emanation 

 to fall to 

 half its 

 initial 

 value. 



iSainarskite . 



F. Carolina, U.S.A. 



20 



20,600 



103,000 



3-48 



Fergnsonite . 





7 



4,280 



61,000 



3 -80 



Pitchblende. 





40 



11,900 



29,800 



3 -50 



Malacone . . 



Hitteroe, Norway . . 



20 



1,440 



7,200 



3 -81 



Monazite . . . 





51 



2,060 



4,000 



3 -50 



,, ... 





82 



37 



45 



3-81 







54 



11 



24 



3 -80 







60 



24-6 



41 



4-05 







All the minerals give radium emanation, though in very varying 

 quantity. 



These tests were not started quickly enough to give information as 

 to the presence of a very quickly decaying emanation. This was 

 tested for independently. 



The mineral malacone is of peculiar interest, because it has been 

 found to contain argon as well as helium.* Helium is formed by the 

 degeneration of radium, and it is reasonable to assume that the other 

 kindred gases have had a similar origin. It was hoped, therefore, 

 that malacone might contain some new radio-active element. It is still 

 possible that it does so, but, if so, this substance gives no emanation 

 ■distinct from that of radium. 



The meteorite of Augusta Co., Virginia, has also been found to contain 

 argon and helium. But no emanation at all could be obtained from 

 20 grammes of it. 



The minerals were all tested for thorium emanation by drawing air 

 over them in the cold * the only one in the above list that gives it is 

 the Norwegian monazite, and even this does not yield it ver}^ 

 abundantly. A crystal of thorite, however, kindly lent me by 

 Professor Lewis, was found to give torrents of thorium emanation. 

 * Earn say and Travers, ' Roy. Soc. Proc.,' vol. 64, p. 131. 



