the Mutual Solubility of Liquids* 



197 



Above 40°* 7 there is only one plait left, the plait-point of 

 which is not P x (as is the case with ordinary mixtures) but P 2 . 

 For ordinary mixtures the plait-point lies near the left- 

 hand edge of the plait. Here it is turned much further towards 



Fier. 7, 



Ethane. 



Alcohol. 



v- 



the ,r-axis, the consequence being that the critical temperature 

 and the plait-point temperature differ much more than they 

 do in other cases. Instances of this will be given for ethane 

 and propyl alcohol, for which combination the v-x diagram 

 has the same character as for ethyl alcohol and ethane. The 

 critical temperatures for propyl alcohol and ethane are 38°'67 

 and 41°'7. The two critical temperatures approach each 

 other as we ascend the alcohol series. For butyl alcohol and 

 ethane we find 38°-l and 39°'8. 



Tables VIII. and IX. for propyl alcohol and' ethane are 

 again in full concordance with the diagrams. 



In fig. 8 [\i. 199) the following curves have been drawn : — The 

 vapour-pressure curve for ethane (that for propyl alcohol is 

 not shown) ; the three-phase curve which starts at 38°*7 and 

 ends at 41 0, 7 C; the plait-point curve C x C 4 of the plait-point 

 P x connecting C 1 the critical point of ethane with C 4 the end 



Phil. Mag. S. 5. Vol. 48. No. 291. Aug. 1899. P 



