470 Royal Society : — 



present annually lost by our globe is upon his theory sufficient to 

 account for it ; so that the secular cooling, small as it is, now going 

 on is a sufficient primum mobile, leaying the greater portion still to 

 be dissipated by radiation. The author then brings his views into 

 contact with various known facts of vulcanologv and seismology, 

 showing their accordance. 



He also shows that to the heat developed by partial tangential 

 thrusts within the solid crust are due those perturbations of hypogeal 

 increment of temperature which Hopkins has shown cannot be 

 referred to a cooling nucleus and to differences of conductivity 

 alone. He further shows that this view of the origin of volcanic 

 heat is independent of any particular thickness being assigned to 

 the earth's solid crust, or to whether there is at present a liquid 

 fused nucleus, all that is necessary being a hotter nucleus than 

 crust, so that the rate of contraction is greater for the former than 

 the latter. The author then points out that, as the same play of tan- 

 gential pressures has elevated the mountain-chains in past epochs, 

 the nature of the forces employed sets a limit to the height of 

 mountain possible of the materials of our globe. 



That volcanic action due to the same class of forces was more 

 energetic in past time, and is not a uniform but a decaying energy 

 now. Lastly, he brings his views into relation with vulcanicity pro- 

 duced in like manner in other planets, or in our own satellite, and 

 shows that it supplies an adequate solution of the singular and 

 so far unexplained fact that the elevations upon our moon's surface, 

 and the evidences of former volcanic activity, are upon a scale so 

 vast when compared with those upon our globe. 



Finally, he submits that if his view will account for all the known 

 facts, leaving none inexplicable, and presenting no irreconcilable 

 conditions or necessary deductions, then it should be accepted as 

 a true picture of nature. 



'■' On the Action of Electricity on Gases." Bv Sir B. C. Brodie, 

 Bart., F.R.S., Hon. D.C.L. Oxon. 



This memoir, which is intended to be the first of three commu- 

 nications as to the action of electricity on gases, is devoted to the 

 consideration of the changes produced by the action of electricity on 

 oxygen gas as estimated by the changes thus effected in its chemical 

 properties. 



The memoir is divided into four sections. 



Section I. contains an account of the methods employed for gene- 

 rating, collecting, and preserving the electrized gas, and also of 

 the measuring-apparatus employed for estimating the changes in 

 the volume of the electrized gas effected in the various experiments 

 subsequently described. 



The gas, carefully dried, was submitted to the action of electricity 

 by causing a current of the gas to pass through the induction-tube 

 of Siemens, the interior of which was filled with water or (where 

 a low temperature was desired) with a saline solution. The tube 

 was placed in a glass cvhnder containino; water or a refrisreratino:- 



