( '04 ) 



— le„-{-kT— j-\=zq (&o that q is the pure latent heat of melting 



of the compound, without the heat of dissociation, which is still to 

 be added), and with c,, — c = y : 



(1 — «)(1 — .v) 



q^vT — RT log . 



^ ^ ^' 1 + « (1 _ .,) 



For the determination of y may serve, tiiat at a,' ^ and T= T^, 

 a becomes «„, hence: 



1 — «„ 

 9 = r^o — -^^0 log -— . 



1 + «0 



Hence we finallj get : 



q{T,-T)^-RTTJocj ^ " ' 



I - a, 1 + « (1 — .r) 

 or 



_ 1+«„(1-«)(1— f) ^g /I 1\ 



In this derivation it has also been supposed, that the liquid mixture 

 is a so-called ideai mixture, i. e. that terms, referring to the influence 

 of the components inter se, have been left out. It is known that 

 these terms are of the second degree with respect to x. Equation (5) 

 represents therefore the course of the "ideal" melting-point curve in 

 our case. 



Further the degree of dissociation « occurring there is given bj' 

 the equation (here too the above mentioned terms are left out, so 

 that the simple law of mass-action is supposed to hold): 



a(\-.v) u{\-.v)-^,v (1_«)(1_^.) 



X Tt = ^ = ^^ 



N N N 



a (a (1 —x) + x) 



(i-«)(i+«(i— ^0) 



K. (6) 



In this K is now no longer a function of x according to the above 

 supposition, but it is one of 7'. 



Even if we would solve n from this quadratic equation, and sub- 

 stitute it in (5), we should have gained but little, because A' contains 

 T in a rather intricate way. Therefore the only thing we can do, is 

 to try a,nd find an approximate expression, which only holds for 

 small values of ,r. 



