C. D. Cooksey — Secondary Cathode Rays. 

 Gold. 



55 



Radiator 

 A, in Al 



K 



K 



/8x 10- 4 



*xl0 5 

 cms. 



s 



p^k-it' 



Se*^ 



e/i 

 Obs. 



R 



Chromium . 

 367 



9780" 



0-0321 



Vo-o 



0-8 

 > 

 — 1-6 



1-03 

 1-03 



1-07 



1-10 

 1-10 



1-30 

 1-34 



1-18 

 1-22 



Iron 



239 



707o- 



0-0209 



66-0 



0-8 

 > 

 = 1-6 



1-01 

 1-02 



1-05 



1-06 

 1-07 



1-31 



1-24 



Zinc 



106-3 



3438- 



0-0093 



57-5 



0-8 



> 



= 1-6 



1-01 

 1-01 



1-01 



1-02 

 1-02 



1-21 

 1-25 



1-19 

 1-23 



Tin 



4-33 



106-4 



0-0004 



10-7 



0-8 



> 



= 1-6 



1-00 

 TOO 



i 

 1-00 



1-00 

 1-00 



1-15 

 1-16 



1-15 

 1-16 



Silver. 



Chromium . 

 367 



6095- 



0-0321 



38-0 



1-8 



> 



= 3-6 



1-02 

 1-03 



1-07 



1-09 



l-io 



1-33 

 1-40 



1-22 

 1-27 



Iron 



239 



4000- 



0-0209 



35-8 



1-8 



> 



= 3-6 



1-03 

 1-02 



1-05 



1-08 

 1-07 



1-31 



1-21 



Zinc 



106-3 



1830- 



0-0093 



31-4 



1-8 



> 



= 3-6 



1-02 

 1-01 



1-01 



1-03 

 1-02 



1-24 



1-20 



Tin 



4-33 



1 

 23-02 0.0004 



5-75 



1-8 

 > 

 = 3-6 



1-00 

 1-00 



1-00 



1-00 

 1-00 



1-23 1-23 

 1-23 1-23 



silver is 1*07, and for platinum, which seems to behave, for 

 X-rays at least, about the same as gold, 1*17. This is about 

 the same as the mean of all the values which I have obtained 

 for gold. His value for silver is somewhat less than the mean 

 of my determinations. If the mechanism of production of 

 cathode rays is the same with ultra-violet light as it is with 

 X-rays, the ratio of emergence to incidence effect does not 

 seem to vary much over a range of absorbability corresponding 

 to the X-rays from tin up to that corresponding to ultra-violet 

 light. 



Summary. 



The ratio of emergence to incidence cathode rays produced 

 in gold and silver by beams of fluorescent secondary X-rays has 



