208 Mr. G. W. Walker on the Rate of 
N d 
vs aay an) 
cs — = 1A, (1+ (6) 
If we use the values of / and d given in the paper, we get 
bes Wes. 20 ) 
sm 35°07 Ec 701° ge (1 i 25°07 +h ae (7) 
It is quite easy to test the results. We have only to sub- 
stitute a value of w, and calculate the value of the expression 
on the right-hand side. Then, since we know N, we can 
calculate the value of N;; and hence from the experimental 
curve we get the value of ¢t, and hence of X. The values of 
y for a given pressure should agree. Having obtained A, we 
may g vet the absolute value of a x by any of the three formule 
(4), (5 ), and (6); and the values so obtained should be the 
same. As I have already pointed out, these values cannot be 
affected by the intensity of radiation, 
With a view to testing these points, the following table was 
prepared from the results given in McClung’s s paper (Phil. 
Mag. March 1902, pp. 293- ~296). In preparing it the values 
of pw were substituted in the expression on the right-hand 
ae of (7), and then the values of t obtained from the expe- 
rimental curves, 
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ee 50 ‘ae. | 20 250 236 1:06 
RE 100 266 47 212 | (eae 
Bese Ssh b SDN aeT Te cites 217 | i860 eee 
igh Penta | F00' | eee] 54 | 185 | SL | 
ieee | SO) ae ST 9B 178 181 98 | 
ee 100-266 | | | 
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2 ne 100: | -266 | | | 
Oh genet 50 iy, | <3 O44 eats ‘69 
awe 100 | -266 | | 
PDB wee BOG Bae al cag 106 | 194 eae | 
