6 L. VEGARD. M.-N. Kl. 



It is onl}' the positive electricity above this zero layer that will be 

 responsible for the electric field of the earth outside the zero sphere. 



If the sun emits X or ;'-rays, these rays, when they strike the upper 

 strata of the atmosphere, will cause the gas to emit electrons with a velocity 

 given by the equation of Einstein: 



h y = -^ m î'2 = c V (7) 



Some of these electrons leave the earth, and this process will continue 

 until the potential of the earth V is equal to the potential which is deter- 

 mined from the frequency. If the rays had a wave length of i A' the 

 potential should be 41 electrostatic units. 



At the very limit of the atmosphere, e. g. 600 km. above the ground, 

 there should be en electric force: 



V _8 



F ~ -^ —6-10 el. St. units 



Probably there may be a radiation of much shorter wave length and 

 the electric force would be correspondingly greater. 



Now if we have a Nitrogen ion with a positive charge + c, at the same 

 point, it will be driven upwards with a force Fe and downwards with the 

 force /// g. If the ion is not to leave the earth we must have : 



;ii g'> Fc . 



Putting 



ni ^ M ■ lu^ 



where ui^ is the mass of a hydrogen atom. 



If the ion is a charged molecule M = 28 and 



F <C iO el. St. units. 



We see that only an extremel}' small electric force would be sufficient 

 to counterbalance gravity, and the electric force, which might be produced 

 through the electron-emission due to photo-electric effect, is several hundred 

 times larger than that which is necessary to drive a charged molecule away 

 from the earth. 



It seems as if the emission of X- and /-rays from the sun would 

 gradually drain the atmosphere of its Nitrogen. 



