ADAMS. — TRANSMISSION OF RONTGEN RAYS. 



683 



was made of the ratio of transmission of the silver screen under these 

 circumstances. The screen was interposed at the same place, relatively 

 to the instrument, as before ; hence the motion of the tube involved a 

 considerable variation of the intensity of the radiation incident on the 

 screen. The extremes of intensity were in the ratio of 1 to 8 in this 

 experiment, if the law of inverse squares is applicable. The tube 

 was then returned to its original position, and the first ratio of tran3- 



TABLE IV. 

 Effect of Variation of Intensity upon Transmission by Platinum. 



mission redetermined as a safeguard. By repeating this process several 

 times, the set of readings in Table III was obtained. 



The experiment with platinum is of especial interest because of the 

 use made of that metal as the absorbing material of the instrument. 

 Table IV shows the procedure and the result of this experiment. 



From the experiments on copper, tin, and aluminium it appeared 

 that for those metals, as for silver and platinum, the ratio of trans- 

 mission is independent of the intensity of the incident radiation for 

 a considerable range of intensity. 



