RESEAIICIIES ON EVArOliATION AND DISSOCIATION. 321 



meLl)0(ls and .apparatus tlio memoir on otlier must bo con- 

 sulted. As the data are very voluminous, wo cannot <rivo 

 them here, even in abstract ; but we may mention that they 

 comprise — determinations of the compressibility of etliyl 

 and propyl alcohol, other, and water, both in the liquid 

 and in the gaseous states ; the volumes of all the liquids 

 at pressures equal to their vapoui'-prossuros at the tempera- 

 tures of moasuromcnt, or " ortliobario " volumes of liquid • 

 the volumes of the saturated vapour, or " orthobaric " 

 volumes of gas ; from these the densities of the unsaturated 

 and satriratod vapours (H at f and p mms. = 1), within wide 

 limits, were calculated. The heats of vaporization were then 

 calculated for definite temperatures by means of the thermo- 



I^_^dp T 



- s„ (IT 



dynamical equation. 



It may bo here mon- 



•■'1 - S3 ax J 



tionod that tlie apparent critical temperatures and pressures 

 are for methyl alcohol, 240-0° and 59,700 mms. ; for ethyl 

 alcohol, 243-1° and 47,650 mms. ; for propyl alcohol, 2C3-G4° 

 and 38,120 mms. ; and for ether, 193-8° and 27,080 mms. 



10. The data for acetic acid are given in the Trans. Ghent. 

 Soc, 188R, p. 790. The orthobaric volumes of the liquid are 

 determined between 1.3° and 280° ; the vapour-pressures 

 between - 5° and 280° ; the densities of tho vapour, satu- 

 rated and unsaturated, between 50° and 280°. The heats of 

 vaporization were also calcvilatod. 



11. The Nature of Liquids' {Fhil. Mag., 1887, p. 129).— Tho 

 striking analogy between tlio evaporation of liquids and 

 the dissociation of chemical compounds has led Naumann 

 and others to suggest as probable that the molecules of a 

 liquid consist of congeries of gaseous molecules, and present 

 analogy with tho molecules of a compound body ; differing 

 however in this respect, that while the molecules of com- 

 pounds result, as a rule, from tho combination of unlike 



