32 Mr. Take Sone on the Magnetic Susceptibilities 



that the additive law holds. We have then the following 

 relation : — 



%a=Po* ' Xo 2 +Pn 2 • Xn+Pa • Xa 



Xa Pjy, p A 



or 



Xo, 



, n 'Xn» ' Xa-> 

 "o. 2 Poo Po 2 



where Xa-> <% , ^ , and % A are the specific susceptibilities of 

 air, oxygen, nitrogen, and argon, and p , p N , and p 4 are 

 the ratios of the masses of these gases in air to the total 

 mass of air respectively. 



Then the value of the susceptibility of argon can be 

 deduced in the following way, taking the percentages of 

 nitrogen and argon in air as follows : — 



75*5 and 1*3 per cent. 



Hence the percentage of argon in atmospheric nitrogen is 



1-3x100 



75-5 + 1-3 



1*7 per cent, 



But the presence of argon in the atmospheric nitrogen 

 produces an increase of the dia magnetic susceptibility from 



Xk = -0-265 xlO" 6 to Xw .,= -0-360x10-°. 

 Hence the susceptibility of argon will be 



= ~-0-360xlQ- G _ 0-983 x (-0-265) X3Q- 6 

 Xa ~ 0-017 ' 0017 



= -5-86x10-°. 



Taking as the weight percentage of oxygen in air 23*15 

 and introducing the values for %#, %^ , and % A in the equation 

 for oxygen, we get 



= 23-85 x 10^ 6 _ 0-755 x (-0-265) x 1Q - 3 

 Xo ~ 7 2315 0-2315 



0-13 x (-5-86) xlO" 6 

 0-2315 

 = (103-0 + 0-9 + 0-3) xlO" 6 . 

 = 104- 2 x 10" c . 

 But the susceptibility of oxygen directly determined being 

 %O3 = 104-,xl0-«, 

 these two are in fair agreement with each other. 



