concerned in the Phenomena of ordinary Electricity, fyc. 201 



electricity may easily be accumulated iu a body of small dimen- 

 sions, in consequence of which the electricity acquires a hi°-h 

 tension or a strong tendency to combine with electricity of the 

 opposite kind, and makes its way through non-conductors, such 

 as the air, in the form of a spark/' &c.* In Liebig and Gre- 

 gory's edition of Turner's Chemistry it is said, " Of any number 

 of electrified substances, that will have the highest intensity 

 which has the most free electric fluid on unity of svu-face;" and 

 (page 96) the same is said of galvanic electricity f. In fine, we 

 may shorten the definition of intensity, as Dr. Bostock and Mr. 

 Goodman have done, by the synonym " concentration." 



From these definitions it is plain that quantity and inten- 

 sity are easily convertible into each other. But it is to be in- 

 quired what is the meaning of " a great quantity at a low in- 

 tensity." Can we conceive a great quantity of electricity unless 

 we give it an adequate place of residence ? Can it have di- 

 mensions not limited by a boundary— by a containing body ? 

 We know nothing of quantity beyond that portion which we call 

 into action, and to which we give a locality. When the electri- 

 city generated by a voltaic series is passed through a slender 

 wire, the wire is its momentary place of abode, the quantity con- 

 tained in it at any point of time, and at that moment active, is all 

 that we can take cognizance of, because no more is at that time 

 generated; and be the passage ever so rapid, the effect is at this 

 instant the same as it was the instant before, or as it will be the 

 instant after. Where, then, is the great quantity reposited ? 

 and if there be no place for it, how can it act or exist ? There 

 can be no accumulation of effect unless there be an accumulation 

 of the agent which is the cause of that effect ; but that would 

 constitute intensity. 



It is plain, then, that " a great quantity at a low intensity " 

 must have reference to a great extent of surface on which the 

 electric fluid subsists. Reduce the surface to one-half or quarter, 

 the whole electricity being retained, and you double or quadruple 

 the intensity. Hence this vague expression aims at conveying 

 to the mind a condition which is incomprehensible, unless refer- 

 ence be at the same time made to an equivalent extent of surface 

 occupied. But in the dimensions of a small wire conveying 

 electricity away as fast as it is generated, how is it possible to 

 conceive a great quantity unless at a very high intensity? 



We know but little of the nature of the force which causes 

 electrical phenomena. It has never been, and perhaps never 

 will be determined, whether electricity is matter; or whether it 

 {•analogous to light, heat or magnetism; or whether it consists 

 of vibrations of some ;ethereal fluid, or of matter in vibration; 

 * Handbook, i. 418. f Eighth edition, page 83. 



