THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOUENAL OF SCIENCE. 



[FOURTH SERIES.] 



MARCH 1865. 



XXVI . On the Elastic Force of Steam of Maximum Density ; with 

 a new Formula for the expression of such force in terms of the 

 Temperature. By Thomas Rowe Edmonds, B.A. Cantab* 



THE laws of steam and other vapours, in relation to elastic 

 force, density, quantity of heat, and temperature, possess 

 claims on the attention of mankind which are not surpassed in 

 interest or importance by the claims of any other branch of phy- 

 sical science. The foundation for the knowledge of these laws 

 must be sought in observations and experiments of great variety, 

 extent, and accuracy. The best of such observations (as is gene- 

 rally acknowledged) are those of M. Regnault, made by order 

 and at the expense of the Government of France. The report of 

 M. Regnault to the Government of his nation was made in the 

 year 1847. His Report fills the twenty-first volume of the 

 Memoires de VAcademie des Sciences de VInstitut de France. It 

 is divided into ten memoirs on steam and allied subjects. The 

 eighth memoir, entitled " Elastic Forces of Steam," contains the 

 materials now presented for consideration. 



Among the laws of steam desired to be known, the most im- 

 portant has generally been acknowledged to be the law which 

 indicates the relation between temperature and elastic force of 

 steam confined with water in a closed vessel — such as the boiler 

 of a steam-engine. On the application of heat to such a vessel, 

 the enclosed water will continually diminish by conversion into 

 steam, and the enclosed steam will continually increase in density 

 and elastic force until the point of condensation or saturation is 

 attained, or, which is the same thing, until the maximum den- 



* Communicated by the Author. 

 Phil. Mag. S. 4 Vol. 29. No. 195. March 1865. N 



