( 195 ) 



the liquid iDixtures in a bath of sohd carbün-dioxyde and aicuhol. 



When tlic solid compound had once been obtained in this way, 

 the (UiFerent points of the stable melting-point line were dclcrmiiiod 

 by seeding the undercooled mixtures with solid hydrate, and by 

 determining the temperature, in which the last trace of solid substance 

 vanishes by slow heating. 



Instead of the metastable three-[)hase e(|uilil)rium between two 

 liquid layers and solid phenol discussed just now, we now likewise 

 get such a three-phase equilibrium in stable state, but now between 

 two liquid layers and solid hydrate. For this stable three-[)liase 

 equilibrium indicated l)y the points l.dh the tenq)erature 12,2° was found. 



If we now go to lower temperature, we get the continuation of 

 the melting-point line of the compound which lies very much to the 

 side of the component, water, and ends in the eutectcc point for 

 ice, liquid and .solid lujdrate, the temperature of which a])peared to 

 lie at —1.0°. 



In conclusion we may still mention that to get perfect certainty 

 that the top of the melting-point line of the hydrate really lies in 

 the stable region it must be examined if there exists a eutectic point 

 of solul hydrate, liquid, and solid phenol, which in this case must 

 lie below the highest melting-point observed on the n)elting-|)oint 

 line of the hydrate. This question was settled beyond all doul)t by 

 the following procedure: we started from a mixture lying in concen- 

 tration between (j and li; this mixture was entirely melted, then 

 undercooled by cooling to ± 15°, and then seeded with a con- 

 glomerate of the solid com|)Ound and the solid phenol. Then the 

 temperature rose to 15°. 8 and remained constant there for a consi- 

 derable time, from which follows that the top of the melting-point 

 line of the hydrate really still lies just in the stable region, as has 

 been indicated in the 7'-,6'-(igure. 



Anorij. Chein. Lnboratorij of the Uaiversit//. 

 Amsterdam, June 1911. 



Chemistry. — ''On the .system hydroyensid/ddde-water." By Dr. 

 F. E. C. ScHEFFKK. 'Communicated by Prof. A. F'. Hollkman.) 



1. In a previous communication ') I already mentioned the prin- 

 cipal part of the results of my investigation on the system hydrogen 

 sulphide-water in the neighbourhood of the cpiadruple j)oint hydrate- 

 two liquid layers-gas. From the determination of the /^- 7^-projection 

 of the four three-phase lines the behaviour of the said system could 



ij These Proc. Jan. 1911. 



