44-8 Royal Society. 



fluence of terrestrial induction in giving rise to electrical currents, 

 form the subject of this second paper. 



The author has comprised the phaenomena here related in the follow- 

 ing general formula. Referring to the pole of the magnet as the 

 centre of action, if all the parts of the metallic conductor move in 

 the same direction and with the same angular velocity, no electric 

 currents are produced : but if one part cut the magnetic curves 

 while another part is stationary, or if the motion of the whole be 

 in one direction, but its angular velocity relatively to the pole of 

 the magnet be different, then, in either case, currents will be pro- 

 duced ; the maximum effect taking place when different parts move 

 in different directions across the magnetic curves. 



January 19. — A paper was read, entitled " On the Theory of the 

 Perturbations of the Planets." By James Ivory, Esq. A.M, F.ll.S., 

 Instit. Reg. So. Paris., and Reg. Sc. Gotting., Corresp. 



January 26. — The reading of a paper, entitled " Experimental 

 Researches in Voltaic Electricity", by the Rev. William Ritchie, 

 LL.D. F.R.S. Professor of Natural and Experimental Philosophy in 

 the Royal Institution of Great Britain, and in the University of 

 London, was commenced. 



February 2. — The reading of the Rev. Dr. Ritchie's paper, entitled 

 "Experimental Researches in Voltaic Electricity," was concluded. 



The author adduces many facts in refutation of the theory by 

 which Volta endeavoured to explain the development of electricity 

 in galvanic circles. He shows that the contact of dissimilar metals 

 is not necessary for producing that effect, for galvanic action may 

 be obtained by employing only one metal, if the two ends of the 

 same copper wire be coiled into helices of different diameters, and 

 immersed into dilute nitric acid. The experiments of Mr. Parrot 

 of St, Petersburgh are cited as leading to results totally different to 

 those on which Volta rested the foundations of this theory *. The 

 author points out several important marks of distinction between 

 voltaic and common electricity, and denies that the latter is capable 

 of passing into the former. He shows by an experiment that the 

 free electricity developed by heat is independent of that developed 

 by galvanic action. Chemical decompositions are effected in a 

 totally different manner by voltaic and by ordinary electricity; for 

 in the former case the two elements of the decomposed substance 

 are found disengaged at the opposite poles, but in the latter they 

 are developed at the same point, and appear more as the effect of 

 a cleavage of the molecules by the mechanical agency of electricity. 

 The author conceives that in a galvanic circle of zinc and copper 

 with interposed water, the superior attraction of the zinc for oxj'gen 

 produces an arrangement of the molecules of the water such that 

 the particles of oxygen entering into the composition of each are 

 all turned towards the zinc. This definite arrangement produces 

 in its turn, by induction on the neutral electric fluid contained in the 

 metal, a corresponding definite arrangement of the two electricities 

 along the whole electric circuit. Hence electro-magnetic effects 

 may be obtained without any chemical decomposition; this latter 

 effect taking place only when the attraction of the metal for one 

 * See p. 300. 



of 



