f 288] 
XXXVI. 
ON THE RADIUM-CONTENT OF DEEP-SHA SEDIMENTS. 
By J. JOLY; Se.D7) F8:, 
Professor of Geology and Mineralogy in the University of Dublin ; 
Hon. Sec., Royal Dublin Society. 
[Read, Frpruary 18; Received for Publication, Frpruary 20; 
Published, Marcu 31, 1908.] 
In a recent paper communicated to this Society! I have recorded 
some experiments which appear to show that the sea-water round 
the coast of Ireland, and as far west as sixty-five miles west of 
Valencia, possesses a richness in radium not hitherto suspected. 
This result has been extended by recent measurements made on 
samples of water coliected between Madeira and England, and 
also on water from the Arabian Sea. 
Although the actual amount of radium per cubic centimetre is 
minute (approximating to 0:02 x 10°’ grams), the quantity distri- 
buted in the ocean is, of course, enormous. We do not as yet know 
in what state the radioactive matter exists in the water—whether 
in true solution, or as (possibly) a sulphate or dust in suspension ; 
and, again, whether the uranium, which must be accountable for 
the continued supply of radium, is present in the water, or mainly 
in the sediments. ‘To whatever views we may be led by the 
progress of research in these directions, it is certainly in harmony 
with the high radioactivity of sea-water to find that the deep- 
lying sediments of the ocean are exceptionally rich in radium— 
far richer than average terrestrial rocks. 
The materials dealt with in the following experiments are 
partly from the‘ Challenger,’ partly from the ‘Albatross’ collections. 
1 Proc. R. D.8., vol. xi., p. 253. 
