68 



Anniversary Meeting. 



[Nov. 30, 



stopped, and hi achieving a determination so exact as to compete 

 with the astronomical determinations, and thereby lead, we may say, 

 to an experimental determination of the solar parallax fully rivalling 

 that which is likely to result from the observations of the transit of 

 Yenus which have be*en carried out at so much cost and trouble. 



A double award of the recently instituted Davy Medal has again been 

 made, the recipients on the present occasion being M. Louis Paul 

 Cailletet and M. Raoul Pictet. This award is made to these dis- 

 tinguished men for having, independently and contemporaneously, 

 liquefied the whole of the gases hitherto called permanent. 



The methods pursued by these experimenters, in accomplishing 

 results which equal in interest and importance those obtained by 

 Faraday in the same direction fifty-five years ago, were quite distinct, 

 and were, in each case, the result of several years' preparatory labour. 

 M. Cailletet, by comparatively very simple arrangements, such as 

 admit of ready employment in lecture-demonstrations, has succeeded 

 in obtaining evidence of the liquefaction, and possibly solidification, of 

 carbonic oxide, marsh- gas, oxygen, nitrogen, and hydrogen. His 

 system of operating consists in submitting the gases to very powerful 

 compression at comparatively moderate degrees of cold, and in then 

 allowing them very suddenly to expand. 



M. Pictet has applied the very perfect system, elaborated and put 

 to industrial use by him, for obtaining low temperatures to the attain- 

 ment, though on a larger scale, of results like some of those arrived 

 at by M. Cailletet. By an arrangement of vacuum and force pumps 

 he reduces liquefied sulphurous acid to a low temperature, and applies 

 this as the means for cooling down liquid carbonic acid which, in 

 turn, serves to reduce to a very low temperature a thick glass tube, in 

 which the gas to be condensed is confined at a very high pressure. 

 M. Pictet has not only produced liquid oxygen in somewhat consider- 

 able quantity, and succeeded in determining its density, he has also 

 obtained evidence of the solidification of hydrogen, and the description 

 given of its appearance in the solid form seems to leave no doubt 

 regarding its metallic character, 



The interest which attaches to the remarkable experiments of 

 MM. Cailletet and Pictet is only equalled by the importance of the 

 fact, now absolutely demonstrated by those experiments, that the 

 property of molecular cohesion is common to all known bodies without 

 exception. 



The Statutes relating to the election of Council and Officers were 

 then read, and Mr. Ellis and Mr. McLachlan having been, with the 

 consent of the Society, nominated Scrutators, the votes of the Fellows 



