84 



NATURE 



yi 



[May 27, 1897 



of place to state that the calculations give an approximation, 

 and that no absolute reliance can be placed on the formula. 



The effects to which the level of the sea is subject are so 

 many and so varied, and there may be in operation agencies 

 acting over a distant area which cannot be discovered by local 

 observation, or which may have been in operation on previous 

 days, that it will never be possible to give a correction of 

 mathematical exactitude. 



But every indication which approaches truth, and which in- 

 creases our knowledge, is useful, and in this light the formulae 

 given should be considered. F. L. Ortt. 



The Hague, Holland. 



CONTACT ELECTRICITY AND ELECTROL YSIS 

 ACCORDING TO FATHER BOSCOVICH. 



YESTERDAY evening, in the Royal Institution, I 

 spoke of an ideal one-fluid electricity subject to 

 attractions of solid substance, to account for contact 

 electricity of metals ; and I said that before the end of 

 our meeting I might speak of it further and might have 

 to reverse the conventional language I was using as to 

 positive and negative, and call resinous electricity posi- 

 tive, and vitreous negative. My allotted hour was 

 woefully overpast, and half an hour more gone, before 



CoNP(Gu;?ATfON Bcro^E Acr;ON Or Clect ff lyt/ c FofjcE 



Ej-ECTf^OLYTiC rOf?CE 



Si^^ 



By kf\f\OYJs 



I could return to the subject ; and I felt bound to stop. 

 What I wished to say may be said in the columns of 

 Nature in fewer words than I could have found, to 

 make it intelligible, last night. 



Varley's fundamental discovery of the kathode torrent, 

 splendidly confirmed and extended by Crookes, seems 

 to me to necessitate the conclusion that resinous electri- 

 city, not vitreous, is the electric fluids if we are to have a 

 one-fluid theory of electricity. Mathematical reasons, to 

 which I can only refer without explanation at present, 

 prove that if resinous electricity is a continuous homo- 

 geneous liquid, it must, in order to produce the phe- 

 nomena of contact-electricity which you have seen this 

 evening, be endowed with a cohesional quality such as 

 that shown by water on a red-hot metal, or mercury on 

 any solid other than a metal amalgamated by it. It is 

 just conceivable, though it does not at present seem to 

 me very probable, that this idea may deserve careful 

 consideration. I leave it, however, for the present, and 

 prefer to consider an atomic theory of electricity foreseen 

 as worthy of thought by Faraday and Clerk Maxwell, 

 very definitely proposed by Helmholtz in his last lecture 

 to the Royal Institution, and largely accepted by present- 

 day theoretical workers and teachers. Indeed, Faraday's 

 law of electro-chemical equivalence seems to necessitate 



NO. 1439, VOL. 56] 



something atomic in electricity, and to justify the very 

 modern name electron. The older, and at present even 

 more popular, name ion given sixty years ago by 

 Faraday, suggests a convenient modification of it, 

 clectrion, to denote an atom of resinous electricity. And 

 now, adopting the essentials of Aepinus' theory, and 

 dealing with it according to the doctrine of Father 

 Boscovich, each atom of ponderable matter is an electron 

 of vitreous electricity ; which, with a neutralising electrion 

 of resinous electricity close to it, produces a resulting 

 force on every distant electron and electrion which varies 

 inversely as the cube of the distance, and is in the 

 direction determined according to the well-known re- 

 quisite application of the parallelogram offerees. 



In a solid metal the ponderable atoms must exert such 

 other mutual forces, compounded with the electric forces, 

 that the assemblage in equilibrium shall have the crystalline 

 configuration, and the elasticity-moduluses, of the metal. 

 The electrions must be perfectly mobile among the pon- 

 derable atoms, subject only to the condition that the 

 electric attraction ceases to increase according to the 

 inverse square of the distance and becomes zero (or, 

 perhaps, strong repulsion) when the distance is diminished 

 below some definite limit. For simplicity we may 

 arbitrarily assume the following conditions : 



(i) Each electrion is a point-atom 

 of resinous electricity and repels every 

 other electrion with a force varying in- 

 versely as the square of the distance 

 between them. 



(2) Each electrion is attracted by 

 each ponderable atom with a force 

 which varies inversely as the square 

 of its distance from the centre of the 

 ponderable atom when the distance 

 exceeds a certain limit r and is zero 

 when the distance is less than r. 



(3) The shortest distance between 

 two centres of ponderable atoms need 

 not be limited to be >2r : it may be 

 whatever we find convenient for the 

 structure and properties to be realised. 

 It will be >2r in an insulating solid 

 and <2r in a conductor. 



Two pieces of metal, M, m', each 

 constituted as I have now explained, 

 will behave in respect to contact- 

 electricity just as two pieces of metal 

 behave in. a perfect vacuum. For 

 example, if r>r', u will behave to m' as zinc behaves 

 to copper. 



To illustrate electrolysis, consider an ideal case of 

 a detached compound zinc-copper atom, composed of 

 two single atoms with their centres at C, c' ; and two 

 electrions e, e which must, for equilibrium, be in the 

 positions shown in the diagram, if r, r be of such magni- 

 tudes as the radii of the circles showing the shortest 

 distances to which c and c' attract electrions. Let 

 now electrified bodies at great distances (such as 

 the vitreously and resinously electrified plates indicated 

 in the diagram) act in the manner indicated by the 

 dotted arrows relatively to the ponderable atoms, and 

 the full arrows relatively to the electrions. The ponder- 

 able atom c will be drawn away to the right by the electric 

 force on itself: and the ponderable atom c' will be 

 dragged away to the left by the two electrions over- 

 coming the rightward force which itself experiences in 

 virtue of the electric field. Lastly, to take a real case, 

 the electrolysis of copper-sulphate, let c' be the centre of 

 an atom of copper in combination with oxysulphion 

 (S04),not shown in the diagram ; with, in all, six electrions. 

 The copper atom c' will be drawn away to the right, with 

 no electrion attached to it : and the oxysulphion 

 will be pushed and dragged to the left by the excess 



