( 198 ) 



The obsei'Vcitions marked with a * refer to the four-phase equi- 

 librium ; those with ** have been made in the presence of a great 

 quantity of vapour. 



In the determination of the first series we met with mure diffi- 

 culties than in tlie determination of the second. Whereas tlie dis- 

 appearance of the last crystals is easy to ascertain in solutions rich 

 in water, this is attended with difïiculties in those rich in hydrogen- 

 sulphide, as the crystals of the liydrate were hardly to be seen as 

 long as they were covered by li(piid h\ di-ogensulpliide. Only by 

 making the liquid continually flow from one side of the tube to the 

 other we could succeed in ascertaining whether the last crystals had 

 disappeared. 



The determinations of >SL.^G can still be supplemented as follows. 

 When we bear in mind that the pressure on SL^G reaches one 

 atmosphere at 0,35^ according to the determinations of de Forcrand 

 and ViLLAKD^;, and so that at this temperature the intersection with 

 tiie isobar section of one atmosphere through the L — G surface, 

 takes place, for which sufTticient data are to be found in the literature, 

 it will be clear that we may add to the table for SL^G the con- 

 centration of the solution of H.S in HJJ, which has a pressure of 

 one atmosphere at 0,35°. From Fauser's ^) determinations of solu- 

 bility, we derive that 4,64 volumes of H^S dissolve in one volume 

 of water at 0,35°, from which follow^s x =: 99,63. The value found 

 thus: ,1' =: 99,63, ^^0,35 appears to be in harmony with the otiier 

 values. 



1) DE Forcrand and Vill.a.rd. C. r. 106 851 (1888). 

 -) Landolt — BoRNSTEiN. Tables 19Ü5. p. 602. 



