3JG Proceedings of' the Roijcd Society o/' Edinburgh, 



1833, Ja7i. 7. — Siu Thomas Makdcugall Brisbank, 

 President, in the Chair. — At this meeting, the following com- 

 munications were read : — 



1. Researches on the Conducting Power of the Metals for 

 Heat and Electricity, tending to establish a New Ana- 

 logy between these principles. By James D. Forbes, Esq. 

 F.R.SS.L. and Ed. 



The paper began by pointing out the very limited class of bodies 

 to which observations of the kind alluded to have been extended. 

 The author was led to a careful examination of the existing deter- 

 minations of the conducting powers of the metals for lieat, by some 

 collateral trains of experiment in which he was occupied two years 

 tigo. He points out the degree of confidence which may be placed 

 in the arrangement of conductors given by different authors ; for 

 we appear to be far from reaching a correct estimate of their nu- 

 merical values. In viewing those of M. Despretz as the best, he 

 lemarks, that the position of platinum, which is certainly errone- 

 ous, shews how imperfectly we can depend upon experiments on this 

 point, made with even more than usual care. Platinum is placed, 

 by this writer, almost at the top of the list, between gold and sil- 

 ver, whilst the commonest experiments serve to shew that it is real- 

 ly a very imperfect conductor. 



In order to verify the conclusions of previous observers, and to 

 determine the position of some metals upon which no experiments 

 -seem to have been made, the author employed Fourier's Thermo- 

 meter of Contact, an elegant instrument, which he believes has not 

 before been practically applied. His experiments, however, being 

 only intended for the illustration of a subject of collateral inquiry, 

 were not made with the detail that they would otherwise have 

 been, nor are they presumed to be perfectly accurate. They 

 served, however, to confirm previous experiments on the order 

 of the metals, as conducting substances ; to restore platinum to its 

 right place, and to fix the positions of antimony and bismuth. 

 From these and other data he considers the following as the most 

 probable arrangement of conductors of heat, beginning with the 

 best : — Gold, Silver, Copper, Brass, Iron, Zinc, Platinum, Tin, 

 Lead, Antimony, 2ind Bisjmifk. 



In like manner, by a careful comparison of the results of Harris, 



