54 



The Philippine Journal of Science 



off and collected over 

 water in an aspirator bot- 

 tle. It was then passed 

 into the ionization cham- 

 ber of a Spindler and 

 Hoyer electroscope and 

 tested in the usual man- 

 ner, allowance being made 

 for the decay of emana- 

 tion in the period elapsing 

 between time of collecting 

 and time of testing. The 

 arrangement of the ap- 

 paratus in the testing 

 system is shown in fig. 2. 



Three separate tests 

 were made by this method. 

 The determinations gave 

 0.27, 0.16, and 0.17, re- 

 spectively. The mean of 

 these results is 0.2, a 

 value considerably lower 

 than that obtained by most 

 of the previous investiga- 

 tors. Although the quan- 

 tity per liter is extremely 

 small, the total quantity, 

 since we were using 30 

 liters of sea water, was 

 sufficiently large for accu- 

 rate measurements. On 

 one test the ionization cur- 

 rent was observed for 

 four days, and the electro- 

 scope readings in volts less 

 the natural leak followed 

 accurately the decay curve 

 for radium emanation, 

 diminishing to one-half 

 value in approximately 

 3.85 days. 



In order to check the 

 charcoal absorption meth- 



