304 BESEAECHKS ON EVAPOBATTON AND PISROOIATION. 



constats quo la courbe construito sur ces oxporionces pre- 

 sentait une continuite parfaite avoc celle que donnent les 

 forces elastiques des vapeurs fournies par I'eau liquide 

 aux temperatures swporieuros k degre." He again says, 

 with reference to the other bodies examined: "En resume, 

 mes experiences prouvent quo le passage d'un corps de Vetat 

 solide a Vilat liquide no prodtdt aucun chaiigement appreciable 

 dans la courbe des forces elastiques de sa vapour ; cette courbe 

 conserve une parfaite regularite avant et apres la transforma- 

 tion." The conchision stated at the beginning of this para- 

 graph was derived from thermodynamical considerations by 

 Kirchhoff {Fogg. Ann., vol. ciii.), and by James Thomson 

 (Fhl.1. Mag. (4), xlvii., p. 447), and Sir W. Thomson {Tram. 

 Boy. Soc, Edin., 1851, March 17th). 



Our first experiments were with camphor, by the statical 

 method. The pressures were found for many temperatures 

 up to the melting-point (175°), and for liquid camphor up 

 to 198°; and it is very evident on the diagram that the 

 curves for liquid and for solid camphor meet at a re-enter- 

 ing angle at the melting-point. Similar results were 

 obtained for benzene by the dynamical method. The ap- 

 paratus shown in the wood-cut (Pig. 1) was employed, with 

 the addition of a second tube passing through the cork, so 

 arranged as to deliver benzene on to the bulb of the ther- 

 mometer, which was covered with cotton-wool. 



It was found possible to cool acetic acid far below its 

 melting-point (16-7°), and keep it liquid, and a large number 

 of good results were obtained. The curves meet at about 

 16-3°, and below the melting-point are obviously distinct, 

 each being the result of numerous observations. Attempts 

 made with the greatest care by the statical method gave, 

 as with Regnault, no satisfactory results. 



The next and last case taken in this paper is that of ice 



