Rkiij,y & l4icidNB0TT0M — Cdncentvatmi of Alcoholic Liquors. 237 



Using this expression, the values of the coefficient of Sorel corresponding 



1 a 



to those of — log have been calculated for solutions of alcohol of 



v ° a - X 



different concentrations (see later). 



The distillation coefficients of the alcohol change with the concentration. 

 Only a few results are given showing the change of constant with concentra- 

 tion ; but these confirm tlie results of Sorel and Groning. With dilute 

 solutions of the acids the alteration in the rate of distillation from an aqueous 

 solution can be satisfactorily explained by taking into consideration the 

 degree of ionic dissociation. For the alcohols this explanation cannot apply. 

 The alcoholic solutions are generally more concentrated than those employed 

 in investigations on the acids, consequently the temperature of the aqueous 

 solution may be a determining factor. Another possible disturbing effect 

 may be due to the association of tlie alcohol. Murray^ has adduced evidence 

 that the molecules which are usually associated in the liquid state are 

 generally not associated in aqueous solution. If there still exist in the 

 solution some associated molecules at the concentration employed, there will 

 be a continual change in the state of molecular aggregation as the distillation 

 proceeds. Under these conditions Nernst's law of distribution will not hold, 

 consequently the distillation coefficient may vary. 



As a general rule, the application of jSTernst's law to the distillation of 

 solutions furnishes us with a method of determining whether a substance 

 behaves normally in solution. Water has been used in all the investigations, 

 chiefly on account of the convenience. Other solvents, such as alcohols, 

 amines, or any other substance which is sufficiently volatile to carry over the 

 solute in the vapour may also be employed. 



In the experiments on the distillation of alcohol-water mixtures referred 

 to, the distillations have all been carried out at varying volumes. In the 

 present paper, however, the authors have investigated the distillation 

 coefficients of methyl, ethyl, w-propyl, 7i-butyl, iso-butyl, sec-butyl, and 

 iso-anijl alcohols obtained by distilling constant volumes of dihite aqueous 

 solutions of the alcohols. 



Method of Distillation employed. 



The distillation of dilute solutions of the lower alcohols was carried out at 

 constant volume in a similar type of apparatus to that employed by us for the 

 distillation of the fatty acids. 200 c.c. of a dilute aqueous solution of an 

 alcohol were distilled, and the volume of liquid in the flask kept constant 



lAmer. Chem. Jour., 1903, 30, 19;3. 



