Royal Society. 59 



expelled at its orifice- If, again, a button of platinum be fully ignited 

 by the oxyhydrogen blowpipe, and plunged into watei- previously 

 heated to nearly its boiling-point, bubbles of mixed gas ascend and 

 maj- be collected by an inverted tube. The electrical spark is shown 

 to be capable of decomposing aqueous vapour, and various other 

 modes of producing the same results are given. 



Some theoretical views are then advanced as to the spheroidal 

 state which appears to the author to be intermediate between that 

 of ebullition and decomposition ; as to the probable non-existence 

 of water or steam in the interior of the earth, and as to the antago- 

 nism between physical repulsion and chemical affinity. 



In a supplementary paper, the author considers how far catalysis 

 affects the phenomenon, and regards the decomposition thus pro- 

 duced as presenting a parallel effect produced by the force of heat, 

 to that known to be produced by electricity ; he considers it expla- 

 natory of the decomposition of water by the electrical spark as in 

 the experiments of Pearson and WoUaston. Some further expe- 

 riments ai'e given, in which iridium and osmium and silica are sub- 

 stituted for platinum ; and also some experiments on the liquids 

 bromine and chloride of iodine, both of which yield pure oxygen 

 when exposed to the ignited wire in Mr. Grove's apparatus. These 

 last experiments cannot however be long continued in consequence 

 of these liquids ultimately attacking both the glass and the platinum. 

 In conclusion, the author calls attention to the general evolution of 

 permanent gas from all liquids, except the metals, when exposed to 

 intense heat. 



Dec. 17. — " Researches on Physical Geology." — Part I. The Figure 

 and Primitive Formation of the Earth. By Henry Hennessy, Esq. 

 Communicated by Major North Ludlow Beamish, K.H., F.R.S. 



The author's investigations of the figure of the earth proceed on 

 the hypothesis of its having originally been a heterogeneous fluid 

 mass, possessing only such general properties as those which have 

 been established for fluids ; and independently of the supposition, 

 with which the theory has generally been complicated, that the vo- 

 lume of the entire mass, and the law of the density of the fluid, have 

 suffered no change in consequence of the solidification of a part of 

 that fluid. Assuming the figure of the mass to be an ellipsoid of 

 revolution, the author obtains general analytical expressions for its 

 ellipticity, and for the variation of gravity at its surface. He gives 

 a general sketch of the consequences that may result from the im- 

 proved hypothesis of the primitive figure of the earth, to physical 

 geology, tliat is, to the changes occurring upon the external crust of 

 the earth during the process of its solidification, resulting both from 

 calorific and cIk mical changes taking place among its different parts, 

 and giving rise to a process of circulation throughout the fluid por- 

 tions of tiie mass. 



The present memoir is only the first of a series which the author 

 announces it is his intention to communicate to the Society on the 

 •amc subject. 



