( 382 ) 



jxi'-diagram at — 25° C. is not straiglit, could not l)c proved with our 

 mixtures and our apparatus, as lias lieen said. The measurements at 

 — 38°.5 C. raised it however beyond doubt, that the line under con- 

 sideration is not straight at — 38°.5 C, but is for the greater part 

 convex to the .z'-axis. According to the straight line pix would have 

 to be 5.38 atms. for ./' r=: 0.5084, instead of the \alue 6.13 atms. 

 found. This difference is much too large to be accounted for by errors 

 of observation or of the value ascribed to the composition. There is 

 therefore no doubt but that the li(|uid branch is curved in the same way 

 at — 25° C. In concordance with this deviation is also the fact that the 

 begin pressure at the same temperature does not agree with the 

 hyi)erbolic function for the composition (van der Waals, Continuitiit 

 II, p. 154). For according to this formula the begin i)ressure would 

 have to be 1.78 atms. instead of 2.05 atms., as Avas found (^ 6). 



It appears from all this, that from the conditions of coexistence 

 (hn-iations from the hur of rorn'.-ijKmding states fol/otr for isothermals 

 of mixtures of methyl chloride and carbon dioxide, which become 

 very distinct /'oi- //(/u/d densities mtd loin temperatures. 



The comparison of the conditions of coexistence, derived from the 

 law of corresponding states by means of the if'-surface, with the 

 really observed data, is an indirect method for judging about the 

 deviations from the law of corresponding states for the isothermals 

 of inixturcs. It was our purpose to give an instance of the application 

 of this method and to do this al low temperatures. 



In order to ascertain the accurate amount of the deviations new 

 measuremens al low temperatures v»ill be required, and for the 

 temperature of ol)servation a if>surface will ha\e to be constructed, 

 with more precision than that devised in Comm. Siippl. K". 8 for 

 the sake of preliminary elucidation and for the sake óf corrections. 



Corrigenda et addenda to the paper "On an equivalent of the 

 Cromer Forest-Bed in the Xetherlaitds" in this Vol. of the 

 Proceedings, pag. 214 — 222. 



Page 214, line 14 from top and line 10 from bottom, for 'Mnass" 

 read "massif". 

 „ 215, „ 4 from bottom, after "Belfeld" add "and". 

 „ 215, „ 10 „ „ for "14" read "13.5". 



„ 215, ,, 14 and 1(3 from bottom, for "her" read "its", 

 , 216, „ 2 from top, dele "and probably also to the east". 



