783 



certain considerations and views which will be best learned from the 

 paper itself. After this, he resumes the consideration of Pllicker's 

 results "upon the repulsion of the optic axes of crystals" already re- 

 ferred to, and arrives at the conclusion that his results and those 

 now described have one common origin and cause. He then con- 

 siders Pllicker's results in relation to those which he formerly ob- 

 tained with heavy optical glass and many other bodies. In con- 

 clusion he remarks, " How rapidly the knowledge of molecular forces 

 grows upon us, and how strikingly every investigation tends to de- 

 velope more and more their importance and their extreme attraction 

 as an object of study ! A few years ago magnetism was to us an 

 occult power affecting only a few bodies ; now it is found to influ- 

 ence all bodies, and to possess the most intimate relations with elec- 

 tricity, heat, chemical action, light, crystallization, and, through it, 

 with the forces concerned in cohesion ; and we m^y, in the present 

 state of things, well feel urged to continue in our labours, encouraged 

 by the hope of bringing it into a bond of union mth gravit}'- itself." 



December 14, 1848. 

 Sir R. H. INGLIS, Bart., Vice-President, in the Chair. 



The Chairman announced that the Earl of Rosse had nominated 

 as Vice-Presidents — The Marquis of Northampton, The Dean of 

 Westmhister, George Rennie, Esq., G. B. Airy, Esq., W. R. Grove, 

 Esq., Sir R. H. Inglis, Bart. 



His Grace The Archbishop of Canterbury was elected into the 

 Society. 



The following paper was read : — 

 On the effect of surrounding Media on Voltaic Ignition." By 

 W. R. Grove, Esq., M.A., F.R.S. 



The author refers to some experiments of his published in the 

 Philosophical Magazine for December 1845, and in the Bakerian 

 Lecture for 1 847? relating to the difference of ignition generated in 

 a platinum wire heated by the voltaic current, when the wire is im- 

 mersed in atmospheres of different gases. In the present paper 

 these experiments are continued, the current being passed through 

 two platinum wires both in the same voltaic circuit, but immersed 

 in atmospheres of different gases. 



It appears from these experiments that the heat generated in the 

 wire is less in hydrogen and its compounds than in other gases ; 

 and that when the wires and their atmospheres of gas are immersed 

 in given quantities of water, the water surrounding the hydrogenous 

 gases is less heated than that surrounding those which contain no 

 hydrogen. 



Similar experiments, in which the wires are immersed in different 

 liquids, are then given ; the heat developed appears not to depend 

 on the specific heat of either the gases or the liquids. 



