608 "Scientific Proceedings, Royal Dublin Society. 



n-Butyl alcohol and water being niiscible only within certain limits at 20°C, 

 the curve of contraction on mixing is incomplete. It bears put the observation 

 of Young "and Fortey (Trans. Chem. Soc. 1902, 81, 717) that the contraction, 

 on mixing alcohol with water, diminishes with the rise in molecular weight 

 of the alcohol. The contraction for n-butyl alcohol-water mixtures at 20° C. 

 rises to a maximum of - 7 per cent, for a mixture containing 80 per cent, 

 alcohol. On the other hand, n-butyl alcohol and acetone do not contract on 

 mixing, but rather show a slight expansion. 



Summary. 



1. The densities of a series of acetone, n-butyl alcohol, and water mixtures 

 were obtained, and curves with rectangular and triangular co-ordinates 

 prepared. 



2. The composition of an unknown mixture is readily obtained, with a 

 fair degree of accuracy, by a density determination in conjunction with an 

 estimation of one of the constituents. 



3. The curve of limiting miscibility in the system was determined, the 

 end points giving the limits of solubility at 20° C. of n-butyl alcohol in water 

 (7-9%), and water in n-butyl alcohol (20%). 



4. The maximum contraction for mixtures of n-butyl alcohol and water 

 within the limited range of solubility at 20° C. was found to be 0-74%- 



5. Acetone and n-butyl alcohol were found to be miscible in all propor- 

 tions, there being a slight increase of volume on mixing. 



