132 Prof. Thomson & Mr M c Clelland, On the Leakage of [Mar. 9, 



of molecules or aggregations of some kind in which the component 

 atoms with their electrical charges could rearrange themselves 

 with facility ; the time T required for this rearrangement being 

 independent of the intensity of the electric field. The effect of 

 such a rearrangement would be that in a time T a definite 

 quantity of electricity passed from one end to the other of the 

 chain of molecules. If these chains of molecules were distributed 

 in an unpolarized way through the gas their breaking down 

 would not lead to a current, as as much electricity would pass in 

 one direction as in the opposite. As soon however as the chains 

 are polarized there will be a current. Suppose now that these 

 chains get polarized under the influence of an external electro- 

 motive force and that the polarization is analogous to that of the 

 molecular magnets in a piece of soft iron under an external 

 magnetic field. Then until all the chains get pulled so as to set 

 in one direction the current will increase with the potential 

 difference, but as soon as all the chains get pulled into one 

 direction the current will reach a maximum value and be in- 

 dependent of the electromotive force. 



Rate of leak through solid dielectrics traversed by the Rontgen 

 rays. Solid dielectrics when traversed by these rays become con- 

 ductors of electricity, but the conduction through these substances, 

 inasmuch as it approximately obeys Ohm's law, differs in one very 

 important respect from that through gases. The conduction 

 through solid dielectrics is also remarkable for the extent to which 

 polarization is developed. If the two discs in method AB are 

 imbedded in paraffin, and the paraffin when exposed to the 

 Rontgen rays has a current sent through it, then if the discs are 

 removed from the battery and connected together, and the paraffin 

 kept exposed to the rays a current in the opposite direction flows 

 through the paraffin. If the Rontgen rays are shut off from the 

 paraffin, the polarization can be kept locked up in this substance 

 almost indefinitely, and can after any lapse of time be liberated 

 by again exposing the paraffin to the influence of these rays. 

 Solid sulphur showed exactly similar polarization effects to those 

 shown by paraffin. 



The amount of this polarization may be realized from the fact 

 that the times taken to leak through 50 divisions under a constant 

 electromotive force, were in four consecutive experiments taken 

 quickly one after another 20, 47, 68 and 80 seconds respectively. 

 In comparing the rates of leak under different electromotive forces, 

 it is therefore essential to get rid of polarization between each ex- 

 periment. In the following experiments this condition was care- 

 fully attended to. 



