304 Proceedings of Philosophical Societies. [April, 



employed, the whole apparatus was converted into a thermome- 

 ter, and, when the motion commenced, there was no increase of 

 volume in the mercury ; nor could the motion have been pro- 

 duced by electric repulsion. 



Sir H. Davy would not enter into the conjectural part of the 

 subject any further than to state, that the experiments he had 

 described were unfavourable to the idea, that the phenomena of 

 electromagnetism were produced by the motions of a single 

 fluid ; and that the motion communicated to mercury by electric 

 agency seemed to be produced by a fluid, moving either in right 

 lines or in undulations from each wire as a centre. He con- 

 cluded by observing, that he thought it right to state a circum- 

 stance, which, though known to many Fellows of the Royal 

 Society, was not generally understood : this was, that we owe 

 to the sagacity of Dr. Wollaston, the first suggestion of electro- 

 magnetic rotation ; and that, had not an experiment on the 

 subject, made by Dr. W. in the laboratory of the Royal Institu- 

 tion, and witnessed by Sir Humphry, failed, merely through 

 an accident which happened to the apparatus, he would have 

 been the discoverer of that phenomenon. 



March 13. — On Fluid Chlorine, by M. Faraday, Esq. (Com- 

 municated by the President.) 



Previous to the year 1810, it had been supposed that the 

 crystals which form in aqueous solutions of chlorine at tempera- 

 tures below 40° were pure chlorine, but Sir H. Davy then 

 showed that they were an hydrate of that substance. During 

 the late cold weather, Mr. Faraday had made some experiments 

 on this hydrate, and an analysis of it, an account of which will 

 be found in the 15th volume of the Journal of Science ; it con- 

 sists of 27*7 chlorine, and 72"3 water, or, nearly, of one propor- 

 tion of the former to ten of the latter. The President of the Royal 

 Society suggested, that interesting results might be obtained by 

 examining the decomposition of this compound under pressure, 

 and requested the author to make some experiments on the 

 subject. 



Some of the crystals, dried as much as possible by being 

 pressed in bibulous paper, were introduced into a closed glass 

 tube, the open extremity of which was then hermetically sealed. 

 When this tube was immersed in water at the temperature of 60°, 

 no alteration took place in the crystals ; but when it was placed 

 in water at 100°, they were decomposed, and two fluids resulted ; 

 one of a pale-yellow colour, and apparently water ; the other of 

 a deeper greenish yellow ; resembling chloride of azote. This 

 did not mix with the water, but when the tube was cooled to 70°, 

 they again crystallized in union. Above the fluids there was an 

 atmosphere of chlorine, the intensity of the colour of which indi- 

 cated that it was of great density. Upon dividing the tube, a 

 report took place, as of an explosion, the yellow fluid instantly 

 disappeared, and a strong atmosphere of chlorine was produced. 



