390 Prof. J. Joly en the 
i. (1) 1200 c.cs. not concentrated, do acid : 0-0031 x 10~ 12 . 
Same with 35 c.cs. HC1 : 0*02(10 x 10" 12 . 
(2) 1200 c.cs. not concentrated , with 20 c.cs. HC1 : 
0-0304 x 10- 12 . 
j. (1) 1400 c.cs. not concentrated, no acid: 0014G x 10 -12 . 
The second lot of j was lost by an accident before its 
examination. 
I give these results with some detail in order that the 
variations obtained in the readings may be brought out. 
It is apparent that acid is not always requisite to enable the 
emanation to be liberated ; thus in j the reading is in the 
second decimal place, although acid was not added. But if 
there is concentration then acid appears to be requisite, and 
in some cases a small amount of acid increased to a larger 
at once raised the amount of emanation obtained. It will be 
noticed, also, that the second test of any sample invariably 
affords a higher reading. This is probably due to some 
effect attending the first boiling, whereby a more perfect 
solution is obtained. Second tests are on a slightly more 
dilute solution than first tests, owing to the addition of dis- 
tilled water in the process of displacing the emanation and 
gases into the receiver. In the cases of g (2) and h (2) the 
sea-water, although sufficiently acidified, did not read into 
the second decimal place, although nearly approaching it. 
It is to be observed about these two results that the samples 
of sea-water had stood for nearly two months in the bottles in 
which they were received, and it is possible that radioactive 
matter may have settled out or become adherent to the vessels. 
Taking the means of those determinations where there had 
been sufficient acidification, the results stand as follows : — 
/. Taken Nov. 4th, 1907; lat. 32° 58' N., long. 16° 20' W. 
(About 70 miles N. of Madeira and 430 from coast of 
Morocco.) 
Radium per c.c. 0'0169 X 10" 12 gram. 
g. Taken Nov. 5th ; lat. 34° 50' N., long. 15° 19' W. 
(About 530 miles west of Strait of Gibraltar and 240 
miles from Madeira.) 
Radium 0*0147 x 10 -12 gram per c.c. 
h. Taken Nov. 6th ; lat, 37° 34' N., long. 13° 50' W. 
(About 300 miles west of Cape St. Vincent.) 
Radium 00115 x 10 -12 gram per c.c. 
i. Taken Nov. 7th ; lat. 40° 39' N., long. 12° 16' W. 
(About 180 miles west of coast of Portugal.) 
Radium 0*0282 x 10* -12 gram per c.c. 
