Magnetic Permeability of Liquid Oxygen and Liquid Air. 287 



the transformer and the one on the balancing induction coil, were con- 

 nected in opposition to one another through a sensitive ballistic 

 galvanometer in such a manner that on reversing the primary 

 current the galvanometer was affected by the difference between the 

 electromotive forces set up in the two secondary coils, and a very flue 

 adjustment could be made by moving in or out the adjusting coil of 

 the balancing induction coil. 



The arrangement of circuits is shown in fig. 2. 



FIG. 2. 



/WW 



Ww 



Arrangement of the Circuits of the Transformer and Induction Coil. 



For the purpose of standardising the ballistic galvanometer 

 employed, the primary coil of the balancing induction coil could 

 be cut out of circuit, so that the inductive effect in . the ballistic 

 galvanometer circuit was due to the primary current of the closed 

 circuit transformer alone. A resistance box was also included in the 

 circuit of the ballistic galvanometer. The resistance of the ballistic 

 galvanometer was about 18 ohms, and the resistance of the whole 

 secondary circuit 30'36 ohms. The experiment then consisted in 

 first balancing the secondary electromotive forces in the two coils 

 exactly against one another, then immersing the transformer in liquid 

 oxygen, the result of which was to disturb the inductive balance, and 

 in consequence of the magnetic permeability of the liquid oxygen core 

 being greater than unity, a deflection of the ballistic galvanometer 

 was observed on reversing the same primary current. The induction 



