1211 



rH^O:^rH^O-rE„ . (7) 



(liquid) i'/cis) 



and 



A' H, S + iiiuci) Welter ^ solution -|- .v ^^ . . (8) 



(ffiis) 



Then the tolal change of energy at the transformation becomes: 

 EsUG = J^, \-rE, — sE^. 



When we introduce the quantities of heat instead of the changes 

 of energy, we get : 



EsL,u + (1 + '• - •^•) fiT = E, j- NT -f rE„ + rRT -sE,-s RT 

 or 



in which Q^ i'e[)resents the heat reqnii-ed for the calculation, and 

 lias a meaning analogous to that of the Hiomonymous heat in § 3, 

 Q„ indicates the heal of evaporation of one rnolecute of water, Q^ 

 the heat of solution of one niol. of H,S. 



(a=10780-11.3^^), Q,='i5Q0')) 

 When we now repi'esent the number of molecules of //,-S' I hat dissolves 

 in one mol. of H^O under three-phase pressure by q, the partial 

 pressures of water and sulphuretted hydrogen by Ph^o and Ph,s, 

 we have: 



and = — — . . (9a and 6) 



n-r l—s Ph^s 



These equations may be transformed into 

 Ph.o 



n 



PlhS , I — nq Ph 

 q and r = 



1 



97^ — ' - 9 



Ph.s Ph^s 



or in approximation into: 



PtT n 



s = nq and rz={\—nq) — — .(lOoand^) 



PllrS 



That this approximation is allowable, will appear from the data. 

 (See the tables in the following paper). 

 Now follows from 10^/ and h -. 



1 -\-r-s = {^ -nq)fl^^\ .... (11) 



When we apply the equation of Clapeyron to the three-phase 

 equilibrium in question, we find: 



^) LandoltBörnsteix-Roth. Tables. 

 ') Thomsen. Thermochem. Unters. 



