Section III., 1909. 



[29] 



Trans. R. S. C. 



II. — On the Amount of Radium Present in Sea-Water. 



By A. S. Eve, M.A., D.Sc, McGill University, Montreal. 



(Communicated by Dr. H. T. Barnes and read May 25, 1909.) 



In this paper measurements will be expressed in terms of bil- 

 lionths (10""^") gram of radium per kilogram of water tested. 



Three observers have made determinations of the amount of 

 radium in sea-salt or sea-water. 



Strutt' found 7.5xl0~^^ gram of radium per gram of sea-salt, 

 and this is equivalent to 2.3xl0~^" gram radium per kilogram of 

 sea-water. This, the first determination, was stated to be approxi- 

 mate only. 



The writer^ examined Inagua sea-salt and a sample of sea-water 

 collected from mid-Atlantic and found 0.3 and 0.6, respectively, 

 expressed in the above units. 



A large number of samples have been examined b}»" Joly, and 

 in his Presidential Address to the British Association, 1908, he stated 

 that the average value found by him was 16. 



These three observers then give results in the ratio 4, 1, 27. 



There are several points of special interest in Joly's paper.^ 

 In the first place he found that the addition of HCl tended some- 

 times to increase the amount of radium determined by his experi- 

 mental method, apparently through clearing away precipitates, 

 possibly of sulphates. Next, a second determination invariably 

 afforded a higher reading than the first. Thirdly, two samples 

 of sea-water which had stood for two months in bottles, before test- 

 ing, gave low values. 



I venture to give a brief summary of the results published by 

 Joly, 



Samples of Sea-Water collected Near Land. 



Without HCl. With HCl 



a. Valencia Harbour. 



b. Few miles W. of I. of IMan 



c. 65 miles W. of Valencia 



d. 1.5 miles S. of Crow Head, Co. Kerry 



e. 20 miles W. of Bantry Bay 



1 Proc. Roy. Soc. A, 88, 151. 



2 Phil. Mag., Feb. 1907. 



3 Phil. Mag., March, 190S 



