( 144 ) 



Ordinary pressure, b.p. at 23 mm. 82'', m.p. — 19,5°, n^ = 1,40526. 



EtJtylmetJiylketonecyanohydrin, colourless liquid witli a faint ketone- 

 like odour. Sp. gr. at 18,5° 0,9324. Boiling point at 20,5 m.m. 91°. 

 Does not solidify in a paste of solid carbon dioxide and acetone. 

 n^y> = 1,41775. 



Diethylketonecyanohydrin, colourless, a somewhat stronger odour than 

 the former nitrile. Sp.gr. at 18,5° 0,9300. Boiling point at 18.5 m.m. 

 97.5°, does not solidify in a paste of carbon dioxide and acetone. 

 ?i^ =r 1,42585. 



University Org. Chem. Laboratory, Utrecht. 



Chemistry. — ''The molecular rise of the lower critical temperature 

 of a binary mixture of normal components J' By J. J. \'an Laar. 

 (Communicated by Prof. H. A. Lorentz). 



1. \n the "Chemisch Weekblad" of April 8^^ 1905 (U, N». 14) 

 I derived an expression for the so-called molecular rise of the lower 

 critical temperature, \iz : 



1 T— ^ = 

 TXdxJr 



2[/6xp - (1 + 1?'), 



in which <9 represents the ratio of the two critical temperatures 



—- and If' the ratio -^ . 



In this I started from the approximate assumption, that the critical 

 temperature of a binary mixture may be represented by the simple 

 expression 



Ox 



The formula found is at any rate more accurate than that of 

 VAN 't Hoff, according to which the molecular rise would be constant 

 (Chem. Weekbl. of Nov. 21^^ 1903 (I, K°. 8)), and I adduced a few 

 examples to show" that the expi-ession found by me represents the 

 experimental results of Centnerszwer ^) very accurately — provided 

 the molecular weight of the solvent SO^ is doubled. 



BüCHNER in his thesis for the doctorate ^) came to pretty much the 

 same result with regard to CO, as solvent. He, too, had to double 

 the molecular weight of CO^ in order to get sufficient concordance 



1) Z. f. Ph. Ch. 46, 427—501 (1903). 



2) June 1905, p. 125—130. 



