60 



The Philippine Journal of Science 



1914 



Table III. — Relative absorption of radium emanation by coconut charcoal 

 for exposures of different lengths. 



Date. 



Dura- 

 tion of 

 expo- 

 sure. 



Radium 



in 

 standard 

 solution 

 in grams 



X 109. 



Electroscope read- 

 ing in divisions 

 per minute. 



Method used for 

 putting standard 

 solution in "steady 



state." 



Remarks. 



Due to 

 emana- 

 tion col- 

 lected 

 from so- 

 lution in 

 time of 

 exposure. 



Deduced 

 on basis 

 of emana- 

 tion from 

 solution 

 in 20 

 hours. 



Dec. 19,1912 

 Dec. 26,1912 

 Jan. 10.1913 

 Mar. 3.1913 

 Mean -- 



Hrs. 

 5 

 5 

 6 



6 



0.628 

 0.628 

 0.628 

 0.628 



0.320 

 0.346 

 0.306 

 0.333 



1.280 

 1.384 

 1.224 

 1.332 

 1.305 



Air was bubbled 

 through boiling 

 solution fori hour 

 and then through 

 solution at room 

 temperature for 2 

 hours. 



For collecting, 2 

 electrosilica tubes 

 each containing 70 

 grams charcoal 

 were placed in 

 series. The tubes 

 were heated in 

 parallel to drive off 

 the emanation. 



Mar. 4, 1913 

 Feb. 26,1913 

 Feb. 24,1918 



10 

 15 

 20 



0.628 

 0.628 

 0.628 



0.698 

 1.098 

 1.273 



1.396 

 1.464 

 1.173 



In the course of some experiments carried out on Mount 

 Pauai, we had occasion to use some electrosilica tubes of much 

 larger bore. The tubes which we had been using contained 

 70 grams of charcoal closely packed in a length of about 48 

 centimeters of the tube, 2 tubes always being used in series. 

 In the larger tubes, 140 grams of charcoal occupied a length 

 of about 40 centimeters, and, since the total weight of charcoal 

 was the same, we assumed at first that the amounts of emanation 

 absorbed would be at least approximately equal. But we soon 

 found that for the same strength of solution and the same time 

 of exposure the larger tubes were absorbing only about 50 per 

 cent as much as the other tubes. The results are given in 

 Table IV. 



