( 794 ) 



cibility of tioo gases m iy be expected. Now thai il has appeared that 

 on the suppositions mentioned in § 2 for mixtures in which one 

 component is a gas without cohesion with molecules with extension, 

 limited miscibility might be expected in the gas Mate, the question 

 rises whether this phenomenon is also to lie expected for mixtures 

 with a gas of feeble cohesion. As on the said suppositions no maxi- 

 mum critical temp, is to be expected, this will be the case when 

 Tien ^> 7/,, is found. l ) We have treated this question by the aid of 

 the {//-surface for the molecular quantity (cf. § 2). We arrive then 

 at the equations developed bv van der Waals Contin. II p. 43. 

 The condition that 7\ m ]> 7/, is: 



4 1 



\b-2<iM buM — Va,22M "\ M\* > ~ 1>W l>\\.\i ■ 



27 " ,,^(1 _,,..„) 



in which bji and .r.i/(I — xju) follow from the equations given bv 

 van der Waals loc. cit. We find from this -2 ) 7), m ^> T^ , 



for /'-2-2.1/ &iljf= 2 . if «22.1/ "iu/«\0.58 

 1 0.053 



V, 0.0037 



7 4 0.00023 



0.000015 



It appears on investigation that only for few pairs of' substances 

 the ratios of the a's and b's *) will be able to satisfy this condition. 

 The still unknown relations between a and h for a same -ubstance, 

 to which we alluded in § 1, and from which ensues that in general 

 substances with small n also possess a small h, and that as a rule 

 large h goes together with large '/, seem to prevent this. H e, which 

 with a I) which is still not very small compared with H^ possesses a 

 very small a, so feeble cohesion, and H.,<>, which taking the value 

 of a into consideration, has a comparatively small b, so a molecule 

 of small volume, constitute exceptions to this general rule which are 

 favourable for the phenomenon treated here. 



If for He — H 2 : b^M/buM. = 7j> and a22Jn/^nM = Vi»s (Coram. 

 N°. 96c, Febr. '07. p. 660 footnote 2), T kllt < T h must be expected 

 on the above suppositions. Also for helium-argon and helium-oxygen 

 e. g. the same thing must be expected. Most likely the ratios are 



1 ) Whether limited miscibility in the gas state may also occur if Ti m < Ti l 

 in certain cases and at suitable temperatures, will be discussed in § 7. 



2 ) For bam/ bAM= Vs e g. we find also Tt m > 1\ for 0.125 > u->2M / aiui> 0.061. 

 These cases will be further discussed. 



3 ) See e. g Kohxstamm, LANDOLT-BóR^sTEiN-MEïEKHutFER's Physik. Ghem. 

 Tabellen. 



