( 363 ) 

 examine Uie prodiiel r— ;; 11'.,/; we see thai liiis urodiicl is iieuali\e 



0/;- 

 oiilside ir,/z=(), and positixc inside il. 



There is llicrei'ore onlv a small i-e,ii,i(>ii, in which llic ipianlities 

 ITs;/' and I",/- have difïereid si^i^iis, namelv Ihal rcuion ineh»sed 

 between the h)ci, I'ov which (hese (luanlities are zeru. In this case 



I Tv' J '^ iH\nali\e. In liii'. 7 Ihis is the case for some points on lh(^ 



cnrve JVA'IK" oji Hie h'fl of.!', so for the points hini;- hclwccn 

 tlie point for which Ihe tan.ii'eni is \(Mlical, and Ihc poini J', foi- 

 which the tangent is horizoiital. In ihe same way for some points 

 on tiie right ol' the maximnm, np to tlie point where llie tangont is 

 vevtical. 



In order to ari'i>e at tliis i-esnlt as to tlie conrse of \\\(.' (piantilv 

 Wsfy I had lirst hronght this qiiantity nnder tlie form which has 

 been given Cont. II, p. 110, for the analogons case of the eqnilihriiim 

 between two fluid phases, \v/. -. 



]\\f — pVsf + Es — f f — (.r, — ,,-,) 



7^ 



We may write then (I refer to the page cited of Com. il and Ihe 

 following page for the signification of the notation): 



If we represent in a figure the value of ?/• for a cnrve of etpial 

 pressure, passing through the unstable region, e.g. BEDD' E'JV of 

 fig. 2, we obtain a eurve as is represented in fig. 9. Tlie points of 

 this cnrve, for which ef is small, represent the energy of the li(pnd 

 states corresponding to this pressure. The points lying between the 

 two vertical tangents represent the value of f/- for the unstable 

 phases, and the remaining })oiiits represent the energy fV»r what we 

 may call gas states. The absolute height of ihe ciirxe is not deter- 

 mined by anything, as it represents energy. ( )idy if we also re[)resent 

 the energy of the solid l)ody, the latler energy, being smaller than 

 that of the liijuid phase of the same concenti'alion and of the same 

 pressure and lempcradire, will be incbcaled by a poinI hing below 

 the curve traced. 1 haxc represented il by f . ^\dlelle\■el' Ihe langeni 



to this cnr\i' cuts the axis abo\e f , (?.,/■)/> is negali\ e and \ ice \ersa. 



The same cireiimslances \\hich oecnr lur the sign of I'^.y, are also 

 found here. 



