Miss Pearson, Note on an Attempt to Detect a Difference, etc. 373 



Note on an Attempt to Detect a Difference in the Magnetic 

 Properties of the Two Kinds of Ions of Oxygen. By Miss D. B. 

 Pearson. (Communicated by Prof. Sir J. J, Thomson.) 



[Received 11 November 1909.] 



During the past year attempts have been made to discover 

 v/hether a magnetic field effects any separation of ionised oxygen 

 into its positive and negative constituents. Were such a separation 

 detected it would point to a difference in the magnetic properties 

 of the two kinds of ions. 



The method of experiment was briefly as follows. Oxygen, 

 ionised by passage through a long tube lined with uranium oxide, 

 was passed between the poles of a strong electro-magnet and then 

 into a Faraday Cylinder connected to a Dolezalek Electrometer. 

 At first the gas was driven steadily through the apparatus with 

 the electro-magnet not active. The charge going to produce the 

 electrometer deflection was then merely that due to the excess of 

 one ion over the other, produced by the difference in the rates 

 of diffusion of the two kinds of ions. Readings of the rate of 

 deflection of the electrometer needle in these circumstances were 

 taken. Then the magnetic field was put on across the tube, 

 through which the oxygen was passing, and observations of the 

 movement of the needle once more made. If one ion were more 

 magnetic than the other it would have had a greater tendency 

 than the other to get into the region between the pole-pieces 

 of the electro-magnet, where the field was strongest. Consequently 

 the gas beyond this region would have been poorer in the more 

 magnetic ion, and this dearth of one of the charged constituents 

 of the gas reaching the Faraday Cylinder would have affected the 

 rate of deflection of the electrometer needle. 



As a matter of fact, numerous observations gave no certain 

 indication of any effect produced by the magnetic field. All the 

 readings were small and variable, both with and without the 

 electro- magnet active. The means of the two series of readings 

 were, however, so closely concordant that the results may be fairly 

 taken to shew that the difference between the magnetic properties 

 of the two kinds of ions of oxygen, if it exists, is beyond the limits 

 of accuracy of the method used. 



It would be out of place here to discuss in full quantitative 

 results, but it will perhaps be well to refer to them shortly. The 

 electrometer deflections were of the order of 3'5 scale divisions 



