RESEARCHES ON EVAPORATION AND DTSSOCIATION. 301 



were furnished, and shown to form no exception. The 

 limit of pressure to which these relations apply is about 

 5000 mms. ; at higher pressures another term must be 

 introduced in the equation. 



So far, our work had to do with vapour-pressures ; we 

 next proceeded to determine, within wide limits of pressure 

 and temperature, the relations of temperature, pressure, 

 and volume in the cases of (!)) methyl, ethyl, and propyl 

 alcohols, ethyl ether and water ; and (10) acetic acid. We 

 have also made use of previous determinations by Andrews 

 of these data for carbon dioxide, and by the Natansons for 

 nitric peroxide. 



We have also obtained the data for a mixture of two 

 stable liquids, ethyl alcohol and ether, but those for a body 

 which dissociates into two or more unlike molecules on rise 

 of temperature are still wanting. These we hope to supply 

 at some fntxiro time. These will supplement our knowledge, 

 and wo believe confirm our conclusions as regards the 

 nature of liquids concerning which (11) we have drawn 

 certain deductions from the behaviour of stable liquids con- 

 trasted with that of acetic acid and of nitric peroxide. 

 Prom the measurements already made we are enabled (12) 

 to draw conclusions as to the continuous passage of sub- 

 stances from the liquid to the gaseous state at all tempera- 

 tures below and above their critical points. 



These researches shall now be considered in order. 



(1) The dynamical method of measuring the vapour- 

 pressures of solids gives results identical with those obtained 

 by the statical method {PMl. Trans, of the Royal Society, 

 1884, p. 37). Our experiments showed that at pressures 

 bolow 4-(> mms. ice has definite temperatures of volatiliza- 

 tion without melting, and for each pressure a definite 

 temperature. In the dynamical method, the substance 



