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ROYAL SOCIETY OF CANADA 



flask into 99 ce. of distilled water and HCl. Another new and 

 clean pipette was used to remove 1 c.c. of the well shaken mixture 

 and to transfer it to a second flask containing 99 c.c. of distilled 

 water and HCl. More distilled water was added to each flask, 

 and after sealing the contents were in due course tested. 



The agreement is better than can be expected and is partly acci- 

 dental. One division per minute of the electroscope is a measure 

 of the emanation from 1.90 x lO"-^" gram of radium. 



In testing the specimens of sea-water it was found that the read- 

 ings by day were a Httle larger than those by night. Mr. F. W. Bates 

 has recently proved that the conduction of sulphur is greatly in- 

 creased by direct sunlight, and also to a less extent affected by day- 

 light. My readings were, therefore, taken between 5 p.m. and 

 9 a.m., during which time the aluminium leaf moved about 403ivi- 

 sions of the scale in the eyepiece of the observing microscope. When 

 samples were tested at intervals of less than a month the necessary 

 corrections were made for the incomplete growth of the radium 

 emanation in the flasks. The flask containing distilled water and 

 HCl alone gave the same reading as the " natural leak." 



The results obtained by me were: — 



Range — about . 5 to 1.5, 



Mean 0.94 



