of Hydrogen and some other Gases. 343 



micrometer ocular, the partial pressure due to the oxygen 

 contained in the hydrogen before the discharge is almost 

 less than one-one hundred and fifty thousandth o£ the total 

 volume. The volume susceptibility of this amount of oxygen 

 is therefore 



0-139x10- 

 1-5 x 10 5 



= 0-00925x10" 



This corresponds to about 0*56 per cent, of the suscept- 

 ibility of the hydrogen gas. 



In the actual test for the content of oxygen in the 

 hydrogen gas used in the magnetic measurement, no relative 

 change of the readings of the microscopes exceeding 1/3 

 division of the ocular was observed. Hence we can safely 

 conclude that the error due to the oxygen, which might be 

 present in the hydrogen gas, is at most less than 0*6 per 

 cent, of the susceptibility of hydrogen (Table XIII. B. & C.). 

 Hence we may take as the correct value of the susceptibility 

 of pure hydrogen gas at the ordinary temperature, the value 

 obtained in the present experiments. 



The following tables contain the data of the discharge 

 experiments for the test of the purity of the hydrogen : — ■ 



Table XIII. 



A. 



Hydrogen before passing the 

 palladium tube. 



1 

 Hydrogen after passing the palladium 

 tube heated at about 70° C. 



Time of 

 obser- 

 vation. 



Reading of micro-) 



meter. iRelative 

 change 



Time of 

 obser- 

 vation. 



Reading of micro- 

 meter. 



Relative 

 change 



of 

 reading. 



Discharge 

 tube. 



1 of 

 Control reading, 

 tube. | 



1 



Discharge 

 tube. 



Control 

 tube. 



l h 5 m P.M. 



2 h 30 m p.M. 



Change of 

 reading. 



50 

 8 



50 



83 | 



l h 30 m P.M. 



2 h 30 m P.M. 



50 

 65 



50 

 92 





-42 



+33 -75 





+ 15 



+42 



-27 



