256 Scientific Proceedings, Royal Dublin Society. 
perhaps; but the dulling of the glass on the inside of the flasks 
showed that in every case some solid matter had come down. It 
is true that, in so far as this is redissolved on ebullition, it can 
do no harm; but the risk of error here was evident. 
Accordingly all five were somewhat diluted, and transferred 
to larger flasks, and a few c.cs. of very pure HCl (which I had 
distilled from a nearly pure acid) added to each. ‘This instantly 
cleared the precipitates away. They were then boiled and closed. 
When in due time the whole five came to be redetermined, the 
results came out as follows :— 
(a) Valencia, taken in March, 0:0400 x 107”. 
(5) Isle of Man, taken in April, 0:0386 x 107. 
(c) 65 miles W. of Valencia, June, 00814 x 10-”. 
(d) 1-5 miles 8. of Crow Head, June, 0:0226 x 10°. 
(e) 20 miles W. of Bantry Bay, June, 0°0398 x 10”. 
These, with the exception of (d}, are in close agreement; and I 
find it hard to believe that such a degree of uniformity could 
arise without a real basis for the results. The deficiency of (d) 
might originate in a loss of radium in the process of evaporation, 
the radium being in part left as a precipitate clinging to the 
evaporating dish. The higher results appear to be the more 
reliable ; indeed, there is the possibility that, ina liquid so rich 
in sulphates, even these are not a full revelation. I do not regard 
this,however, as probable. 
These results, of course, do not warrant the conclusion that 
mid-ocean sea-water is equally rich in radium. It might be 
that the acid-treatment is effective in bringing into solution 
suspended radioactive particles of coastal origin. Samples are, 
however, now reaching me through the kindness of friends in 
many parts of the world ; and before long I shall be able to compare 
the above results with waters from various parts of the Ocean. 
The bearing of the subject on many problems it would be 
premature to discuss. My object in publishing the few results 
given above is mainly to call attention to an insidious source of 
error in measurements of the kind. It will be evident also that 
measurements made on sea-salts must be unreliable; for there is no 
assurance that the sample used will contain its due share of the 
radium which would be carried down among the first constituents 
precipitated in the preparation of the salt. 
