On the Limit of the Liquid State. 



321 



Jfra. 5. 



whose condition is also determined by both pressure and temperature. 

 The gaseous state is the only one which is not affected by pressure 

 alone, or in which the molecular velocity is so high that the collisions 

 cause a rebound of sufficient energy to prevent grouping. Another 

 distinction between the gaseous and vaporous states is that the former 

 is capable of acting as a solvent of solids, whereas the latter is not. 

 The two conclusions arrived at from this work are — 

 1st. The liquid state has a limit which is an isothermal passing 

 through the critical point. 



2nd, The vaporous state can be clearly denned as a distinct state of 

 matter. 



To the original distinction between these two states given by 

 Andrews — namely, that of condensibility — I have added another, that 

 of solvent power. A vapour over a liquid holding a coloured solid in 

 solution is colourless, but on passing the critical temperature the 

 whole becomes coloured. In some cases, however, the solid is deposited 

 and redissolved as the temperature rises, showing that the more per- 

 fectly gaseous the greater the solvent power. Andrews's distinction 

 compels us to travel along an isotherm, mine requires high pressure ; 

 both are thus arbitrary, requiring given conditions, but this is the case 

 with many of the other distinctions used in science. 



My thanks are due to my assistant, Mr. Ewing McConechy, for his 

 assiduous aid during the above described investigation. 



VOL. XXXIII. 



