On the Magnetic Susceptibility of Liquid Oxygen. 317 



Table III. Summary of Results of Field Measurements of Axial 

 Field of Tubular Electromagnet. 



necessary to pack round the beaker of liquid with crushed ice in 

 order to keep the temperature of the water or solution from being 

 raised by radiation of heat from the magnet coils. Any rise of tem- 

 perature in the liquid under test, by causing variation in density, 

 introduces a difficulty in obtaining exact and comparable weighings 

 of the ball. 



The position of the ball in the magnetic field was very carefully 

 adjusted, so that the centre of the ball was as nearly as possible on 

 the axial line of the magnet. The distance of the centre of the ball 

 from the end of the magnet core was also measured with as much 

 accuracy as possible when the balance was lifted off its supports, and 

 yet the balance index was in the zero position. 



The distance from the pole face measured in centimetres is called 

 the distance from the pole in the following tables. Corresponding to 

 this distance (#) we know from the preliminary experiments and the 

 results given in Tables I, II, and III the strength of the magnetic 

 field (H) and its axial rate of variation dlBi/dx. 



The dimensions and weights of the balls used were as follows : 



