(in i^t €x%imxl ioxiUxtmi nf Jflixitts. 



]]y Prof. RAMSAY and Dr. S. YOUNG. 



(Ahstraci of Paper read March 4<th, 188G.) 



T' I*" a liquid bo licatcd in a closed space, it evolves vapour, 

 -L wliich exerts pressure on the walls of the containing 

 vessel, as in tlie well-known case of water in the boiler of a 

 steam-engine. At the same time tko liquid expands, and 

 thereby grows specifically lighter. If the temperature bo 

 raised, the vapour grows more dense, for pressiiro is rapidly 

 increased ; and when tho liquid by expansion acquires a 

 density equal to that of tho vapour, rendered heavier by 

 compression, the vapour and liquid mix, and indeed can no 

 longer be distinguished from each other ; tho fluid matter, 

 under such conditions, is homogeneous throughout. To such 

 a state for every liquid correspond a particular temperature, 

 pressure, and volume, and this state is named "critical." 

 It is thus proved that there is no abrupt transition from tho 

 state of liquid to that of gas, but that tho two conditions of 

 matter arc really continuous. This ci'itical condition was 

 exhibited with sulphuric ether, and the effect of altering 

 temperature, pressure, and volume experimentally demon- 

 strated. 



