Magnetic Permeability of Liquid Oxygen and Liquid Air. ^95 



has been standing' in a vacuum vessel for any length of time has a 

 composition which varies with the time and which may contain an 

 much as 75 or 80 per cent, of oxygen, it was not to be expected that 

 very closely consistent results could be obtained in the case of air. 

 The following figures show, however, the observational results : 



PERMEABILITY OF LIQUID AIR. 



Throws of Ballistic Galvanometer. Induction Coils balanced. 



Exp. I. 



Exp. II. 



Exp. III. 



Exp. IV. 



Later. 



Exp. Y. 



Exp. VI. 



Exp. VII. 



Exp. VIII. 



1 *5 mm. to right 

 1-2 



17 -0 mm. to left 

 17-5 , 



0*3 mm. to right 

 0-3 , 



17 '0 mm. to left 

 17'0 

 17'3 , 



2-8 mm. to left 



2-8 



18 -8 mm. to left 

 19-2 

 19-4 

 19-8 



3 '5 mm. to left 

 3-4 , 



22 '0 mm. to left 

 22-0 

 22-0 , 



The transformer in liquid air. 

 Current = 38 - amperes reversed through 

 primary coils. 



The transformer lifted out of liquid air into 

 cold gaseous air at the same temperature 

 as before. 



37 '5 amperes reversed. 



The transformer in liquid air. 

 Current = 37 amperes reversed through 

 primary coils. 



The transformer lifted out of liquid air into 

 cold gaseous air, and at the same tempera- 

 ture as before. 



Current = 37 amperes reversed through 

 primary coils. 



The transformer in liquid air. 

 Current = 367 amperes reversed through 

 primary coils. 



The transformer lifted out of liquid air into 

 cold gaseous air, at the same temperature 

 as before. 



Current = 37 amperes reversed through 

 primary coils. 



The transformer in liquid air. 

 Current = 36*7 amperes reversed through 

 primary coils. 



The transformer in liquid air. 



Primary circuit of balancing coil cut out of 

 circuit and O'lllS ampere reversed through 

 primary of transformer to standardise the 

 ballistic galvanometer. 





The results of these observations, when reduced, show that corre- 

 sponding to a primary current of 37'5 amperes, or a mean mag- 

 netising orce of 164 C.G.S. units, the apparent magnetic permea- 

 bility of liquid air in terms of gaseous air of the same temperature is 



1-00240. 



2 A 



VOL. LX. 



