94 Conducting -Power of Discrete Metallic Particles. 



a minute or so. Doubtless this is due to the fact that, as the 

 film gets more hard and less plastic, the metallic particles 

 find it more difficult to move, by rotation or otherwise, in 

 their environment. 



Finally, these films are very much less sensitive to me- 

 chanical disturbances given to their supports than the tubes 

 of filings. They do not appear to be susceptible to the action 

 of heat ; but in many instances their conductivity was de- 

 stroyed by breathing upon them, or by allowing a stream of 

 steam to strike their surfaces, the conductivity being always 

 restored by the electromagnetic radiations. The more rapid 

 vibrations of light have not produced any effect so far as my 

 observations have gone. 



The prime cause of the action is to be sought in the elec- 

 trical surgings produced in the leads s and w ; but it is clear 

 that the state of affairs at the places P, Q of contact of the 

 film with the electrodes is a most important matter. 



It seems clear, therefore, that the sensitized surface in an 

 impulsion-cell has a close analogue in a slightly plastic film 

 filled with almost mathematical completeness by fine metallic 

 particles. 



YI. On the Sudden Acquisition of Conducting-P ower by a 

 Series of Discrete Metallic Particles. By Prof. Oliver 

 J. Lodge*. 



THE recent experiments of Mr. Croft and Prof. Minchin 

 remind me of an observation I frequently made when 

 engaged with the syntonic arrangement of Leyden-jar circuits, 

 or sympathetic electric resonance. I found, if the knobs 

 of the receiver were very close together, a weak battery and 

 bell being in circuit, that the occurrence of a scintilla at the 

 receiver frequently caused the bell to ring for some time, and 

 in general to show signs that the knobs were in a state of feebly 

 adhesive contact. It was just as if their surface-layers or 

 skins had been broken through, or opened out, in such a manner 

 as to increase the molecular range of a few of the closest 

 superficial molecules and thereby to cause cohesion to set in 

 at a distance considerably greater than the ordinary distance. 

 A phenomenon which may be similarly caused is that dis- 

 covered by Lord Rayleigh, with regard to the effect of electri- 

 fied sealing-wax near a vertical water-jet : drops which would 

 otherwise have rebounded being thereby caused to cohere. 

 And, by the method of two impinging jets, the necessary 



* Communicated by the Physical Society : read November 24, 1893, 

 as a contribution to the discussion on Prof. Minchin's paper. 



