38 Royal Society. 



left it. At one time he counted forty-eight of these meteors during 

 the interval of five minutes. 



Dec. 20. — A paper was read, entitled, "On certain properties of 

 Vapour." By the Rev. Dionysius Lardner, LL.D. F.R.S. 



It has been generally supposed, that if a certain volume of aqueous 

 vapour, contained in a vessel that was incapable of transmitting heat, 

 were compressed by an exterior force into a space sufficiently small, 

 a part of it would be restored to the liquid state. The author con- 

 siders this assumption to be at variance with the doctrine of latent 

 heat, and inconsistent with the results deduced from the experiments 

 which have established that the absolute quantities of heat necessary 

 to convert a given weight of water into steam, under all pressures, 

 are sensibly equal. It follows, from this principle, that steam raised 

 from water, under any pressure whatever, admits of indefinite com- 

 pression and expansion, without returning to the liquid state. The 

 effect of its compression will be to evolve heat and raise the tempe- 

 rature ; that of its expansion, to absorb heat and lower the tempera- 

 ture : but in every state of density it will have exactly that tempera- 

 ture which it would have were it immediately raised from water under 

 the pressure which it has acquired by compression or expansion. 

 The only cause of the restoration of vapour to the liquid form is the 

 abstraction of heat from it j and this cause will be equally operative, 

 whatever may be the state of the vapour with respect to density : but 

 compression alone, without such abstraction of redundant heat, can 

 never convert any portion of vapour into a liquid. In accordance 

 with these views, the author regards the permanent gases as vapours, 

 containing a large quantity of redundant heat. 



1833. Jan. 17. — The reading of Mr. Faraday's paper, entitled, 

 " Experimental Researches on Electricity, Third Series," was resumed 

 and concluded. 



The object of the inquiries of which an account is given in the pre- 

 sent paper, is to establish the identity of the electricities derived from 

 different sources. The author was induced to investigate this sub- 

 ject, because doubts have been frequently expressed as to the accu- 

 racy of some experiments from which the identity of the common and 

 voltaic electricities is inferred : and distinctions have been drawn 

 between them, as if they were different forms and modifications of 

 one common power. In order to examine the question in all its 

 bearings, he arranges the phenomena under two general heads j 

 namely, those arising from electricity in a state of equilibrium, or 

 tension, as it has been called ; and those which are the consequence 

 of its motion, when that equilibrium has been destroyed. The visible 

 effects of electricity of tension are attractions or repulsions at sensible 

 distances ; those of electricity in motion are the evolution of heat, 

 the production of magnetism, chemical decompositions, physiological 

 changes, and, lastly, the evolution of light in the form of a spark. 

 The author proves, by experiments, that every one of these pheno- 

 mena takes place from the operation either of ordinary or of voltaic 

 electricity ; the degree in which they are produced depending on the 

 different circumstances of quantity, of intensity, and of velocity, at- 



