ON ELECTROLYSIS. 337 



in useful directions a considerable amount of energy "wliich otherwise 

 might have remained potential. 



There are several moot points at present more or less under discussion 

 within the Committee, and the editor is instructed to lay them before 

 this meeting with the object of eliciting some opinions, suggestions, or 

 information. 



First may be instanced the obvious question whether electrolytic con- 

 duction and metallic conduction are sharply separated off from one 

 another by a line of demarcation, so that no substance distinctly possess- 

 ing one also possesses a trace of the other. 



Certain contributions by von Helmholtz, among which we must reckon 

 one on our Ust for to-day, lead one to believe that the conduction of 

 ordinary electrolytes is purely electrolytic, and that no trace of current 

 slips through them without carrying the atoms with it, i.e., without 

 effecting incipient decomposition. 



A contribution expected from Professor Roberts- Austen may perhaps 

 answer the opposite question, viz., whether any ordinary metallic alloy 

 can conduct in the least electrolytically — i.e., whether a well-marked 

 metallic alloy or quasi-compound can be in the slightest degree electro- 

 lysed by an exceedingly intense electric current. 



Supposing both these questions answered in the simplest manner, viz., 

 in the negative, there must surely remain a group of bodies on the border- 

 land between alloys proper and electrolytes proper, among which some 

 shading off of properties, some gradual change from wholly metallic to 

 wholly electrolytic conduction, is to be looked for. Until all such bodies 

 as are tractable to experiment have been cautiously and strenuously 

 examined, we are unable to say whether there is a hard and fast line 

 between the two modes of conduction, or in what manner the gradation 

 from one to the other occurs. 



That is the first question. A second concerns the very vital point 

 whether an electric current actually decomposes or tears asunder the 

 molecules of a liquid through which it passes ; or whether it finds a 

 certain number of them already torn asunder or dissociated into their 

 atoms by chemical, or at any rate non-electrical, means, and that these 

 loose and wandering atoms thus fall an easy prey to the guiding tendency 

 of the electric slope, and join unresistingly one or other of two processions 

 towards either electrode, only at the last moment attempting a brief and 

 unavailing struggle, when the electrode suddenly looms foreign and for- 

 bidding across a molecular distance of 10~® centimetres. 



One mode of regarding the facts is to say that across this molecular 

 range of 10"* the electrical forces are competent to tear atoms asunder. 

 The E.M.F. of a volt or so can be shown by calculation to be able to do 

 this, so that the difference between an electrolyte and a dielectric may be 

 typified diagrammaticaUy as on next page. 



Professor Schuster has now discovered one way in which dielectrics 

 shade off into electrolytes ; for he finds that in the neighbourhood of an 

 electric discharge rarefied gases are able to conduct as electrolytically as 

 liquids themselves. This discovery that the atoms of gases possess 

 atomic charge as well as those of liquids, if confirmed by further 

 research, is one of considerable interest. 



But why do we assert the horizontality of the line of slope in the 

 fluid ? Why do physicists feel constrained to assert that no internal 

 1887. z 



