320 On Diselectrification produced by Magnetism. 



" On Diselectrification produced by Magnetism. Preliminary 

 Note." By C. E. S. Phillips. Communicated by Sir 

 William Crookes, F.B.S. Eeceived June 13, — Eead June 15, 

 1899. 



The writer has found, that, under certain conditions, an electrified 

 body rapidly loses its charge when in the neighbourhood of a magnetic 

 field. Nor does it, so far, appear essential that there be any relative 

 motion between the lines of magnetic force and the charged body 

 itself. 



Preliminary experiments have been made with apparatus consisting 

 of a glass tube six inches long and one inch in diameter, at the centre 

 of which there was cemented upon both the inner and outer surfaces, 

 a strip of tin-foil one inch wide. Suitable connections were then 

 arranged for the purpose of charging either of these metallic layers 

 by means of an electrical machine. The pole-pieces of a powerful 

 electro-magnet projected into each end of the glass tube, through an 

 air-tight flange, and in such a manner as to ensure the production of 

 a strong magnetic field at the central portion of the tube. A Sprengel 

 air-pump was used to rarefy the gas within the tube, and, in the first 

 instance, the inner coating of tin-foil was charged positively. 



This charge gave rise to the well known free positive and a bound 

 negative charge upon the outer tin-foil coating, the presence of the 

 former being indicated by the divergence of the leaves of an electro- 

 scope connected to that coating. While the pressure of the gas 

 within the glass tube was varied over a» range of from atmospheric 

 pressure to that represented by 0*2 mm. of mercury, the charge upon 

 the inner coating being either positive or negative showed no appreci- 

 able indication of being affected by the turning on or off of the 

 magnet. But at pressures lower than 0*2 mm., and when the inner 

 coating was positive, the sudden collapsing of the electroscope leaves 

 pointed to the removal of the charge through the action of starting 

 or stopping the magnetic flux. Although the effect was more power- 

 ful at the moment of making or breaking the magnet circuit, it per- 

 sisted in a modified degree as long as the magnetic field existed. No 

 such effect was observed when the inner coating was negatively 

 charged, nor was there any action even in the first case when the 

 magnetic pole-pieces, projecting into the tube, were magnetised so as to 

 be either both north or both south. 



The leaves of the electroscope were then connected to one of the 

 internal pole-pieces, and it was seen that if sufficient positive elec- 

 tricity were supplied to the inner coating while the magnet was excited, 

 it became rapidly withdrawn, and ultimately resided upon the pole- 

 pieces themselves. 



