304 Mr. I. 0. Griffith on the Electricity set free 



Spark between Aluminium terminals in Air, 



Length of 

 column 

 of gas 

 in cms. 



100 

 27 

 16 



Eeading 



when tube is 



exhausted. 



Reading 



when air in 



tube. 



Reading when 

 hydrogen 

 in tube. 



Fraction 



absorbed 



by air. 



Fraction 



absorbed by 



hydrogen. 



•217 

 •133 

 •095 



27-6 

 362 

 47-1 



16-3 



28-2 

 38-5 



21-6 

 31-4 

 42-6 



•409 

 •221 



... .-182 



Spark between Iron terminals in Hydrogen. 



100 



29 7 



21-5 



22-0 



•273 



•259 



27 



33-1 





29-0 





•124 



16 



12-] 



10-1 



1.1-4 



•161 



•055 



The results are shown diagrammatically in fig. 4. The 

 curves show very clearly the effect o£ selective absorption. 

 It is evident that a portion of the radiation is rapidly absorbed 

 and a more penetrating part passes through. 



Spark in Air. 



(1) Absorption by 



air. 



(2) Absorption by 



hydrogen. 



Spark in Hydrogen. 



(3) Absorption by 



air. 



(4) Absorption by 



hydrogen. 



Fig. 4. 









0) -^1- 



(2) 















16 



27 



J2-— 



100 



g 



<^T 



8 



16 Z7 



IOO 



