1898.] and the Ionization produced in it by Rontgen Rays. 13 



filled with lime, but in spite of this it retained sufficient moisture 

 to produce a deposit of water on the insulating supports which 

 in a few minutes destroyed the insulation. 



The numbers given above show that with the exception of 

 cyanogen the saturation current through the gases and therefore 

 their ionization obeys the additive law, i.e. if 2 [A], 2 [B] repre- 

 sent the ionizations of the elementary substances A 2 ,B 2 respectively 

 the ionization of the compound gas represented by the formula 

 ApB q will be equal to p [A] + q [B]. 



If we assume the truth of this law and calculate from the 

 saturation currents for H 2 , N 2 , 2 , C0 2 , S0 2 and Ci 2 the ionization 

 constants for H 2 , N 2 , 2 , C 2 , S 2 , Cl 2 which we shall denote respec- 

 tively by 2 [H], 2 [N], 2 [0], 2 [C], 2 [S], 2 [CI], we find 



Gas 



CO 



NO 



N 2 



C 2 N 2 



C 2 H 2 



H 2 S 



HC1 



NH 3 



Thus the only case in which there is any serious discrepancy 

 between the observed and calculated results is that of C 2 N 2 ; 

 there are other cases in which the additive law holds, such for 

 example as Kopp's law of volumes where the atomic volume of 

 cyanogen cannot be got from those of carbon and nitrogen. 



The ionizations in H 2 , NH 3 , C0 2 , N 2 0, S0 2 and HC1 have 

 been measured by Perrin (Theses presenters a la Faculte des 

 Sciences de Paris, 1897, p. 46) ; his results with the exception of 

 the ionization in H 2 and NH 3 do not differ much from the pre- 

 ceding, in the case of H 2 and NH 3 however there is a very wide 



