596 Dr. N. Bohr on the Decrease of 



Brsi bo Integrate formula (1 t). This gives 



.\n\\ { : —: t \ log : 



where 



A table for the logarithm integral in (20) is given by 

 Gttaisher*. 



Considering a gas ai L5° and 760 nun. pressure we 

 have N*= 1*224. 10 10 . Putting «=4*78, 10 l0 , E=2e, 



- =5*31 .10 17 , and E/M = 1*448. 10 M , we gei K l= = L-131 . 10* 



and Kj=s— 21*80. In most measurements rays Eroin radium 

 C are used. This corresponds to vV=l % 922.10* f. 



Assuming that the hydrogen atom contains one electron, 

 we gei Eor the hydrogen moleoule n=s2. It' we Eurther 

 assume thai the characteristic Erequenov of both electrons in 

 the hydrogen molecule is equal to the Erequency determined 

 by experiments on dispersion in hydrogen, wo gei J 



ri = ,».,= ;V;V-\ I0 l * and 2 logI> = 35*78, 



Using these values and the above values Eor Y , Kj and EC 8 , 

 we gel Log : — 8*75. [ntroduoing this in formula (20) we 

 gei for the distanoe travelled in hydrogen gas by a rays from 

 radium C beEore their velooity lias deoreased to half' of its 

 original value, ./•,— 24*0 om. The first oolumn of the table 

 below oontains values Por .r/.r, corresponding to difEereni 

 values Eor Y V . No aoourate measurements on the velooity 

 curve in hydrogen have been made. Such measurements 

 would form a very desirable tesi o£ the theory since the 

 assumptions underlying the calculations may be expected to 

 be closely fulfilled in case o£ this gas. T. G.Taylor § has 

 recently determined the range of a rays from radium C in 

 hydrogen. Be Eound 30*9 cm. ai L5°and760om. Using 

 the theoretical value .r 1 = i ) l , (i cm., we should expeoi Erom 

 the table thai the rango would ho close to 27 cm. This is 

 noi far from the range observed. At preseni ii seems difficult 

 to decide whether the small deviation may be asoribed U> 

 experimental errors in the constants involved. 



* Phil. Trans. Roy. Sen-. ,-l\. p. 307 (1870>, 

 i B, Rutherford and 11. Uobinson, Phil. Mag, sxviii, p, 662(1914), 

 I 0. & M. Outhbertson. Proo, Roy. Soo. A. Ixxxviii. p. 166 (1009), 

 § Phil. Mag. KXTi, p. 402 (1913). 



