On the Gaseous, Liquid, and Solid States of Water. 27 



December 11, 1873. 

 JOSEPH DALTON HOOKER, C.B., President, in the Chair. 



Notice was given that at the next Meeting the Right Hon. Edward 

 Cardwell would be proposed for election and immediate ballot. 



The President announced that he had appointed as Yice-Presidents : 



The Treasurer. 

 Sir Greorge Biddell Airy, 

 Prof. A. C. Ramsay, 

 Dr. Sharpey, 

 Major-Greneral Strachey. 



Dr. John Beddoe was admitted into the Society. 



The following communications were read : 



I. "A Quantitative Investigation of certain Relations between 

 the Gaseous, the Liquid, and the Solid States of Water- Sub- 

 stance." By Professor JAMES THOMSON, LL.D., Queen's 

 College, Belfast. Communicated by Sir WILLIAM THOMSON, 

 LL.D., F.R.S. Received June 20, 1873. 



In two communications made by me to the British Association at its 

 Meetings at Edinburgh in 1871, and at Brighton in 1872, and printed as 

 abstracts in the Transactions of the Sections for those years, considera- 

 tions were adduced on relations between the gaseous, the liquid, and the 

 solid states of matter. The new subject of the present paper constitutes 

 a further development of some of those previous considerations ; and a 

 brief sketch of these is necessary here as an introduction for rendering 

 intelligible what is to follow. 



Taking into consideration any substance which we can have in the 

 three states, gaseous, liquid, and solid, we may observe that, when any 

 two of these states are present in contact together, the pressure and 

 temperature are dependent each on the other, so that when one is given 

 the other is fixed. Then, if we denote geometrically all possible points of 

 temperature and pressure jointly by points spread continuously in a plane 

 surface, each point in the plane being referred to two axes of rectangu- 

 lar coordinates, so that one of its ordinates shall represent the tempera- 

 ture and the other the pressure denoted by that point, we may notice 

 that there will be three curves one expressing the relation between 

 temperature and pressure for gas with liquid, another expressing that for 

 gas with solid, and another expressing that for liquid with solid. These 

 three curves, it appears, must all meet or cross each other in one point 



