604 



Scientific Proceedings, Royal Dublin Society. 



of n-butyl alcohol. It was found to be slightly cloudy, but on raising the 

 temperature to a very small extent, a clear solution was obtained, a result 

 which confirms the above value for the solubility. Similarly the maximum 

 solubility of water in n-butyl alcohol at 20° C. was found to be 20 grams of 

 water in 100 grams of the mixture. 



As a further check upon these figures a saturated solution of water in 

 n-bntyl alcohol was taken and a small known weight of the alcohol added. 

 The specific gravity of this new solution was found, and, from a graph of 

 densities, the amount of alcohol present was determined. From the known 

 weight of n-butyl alcohol added the original weight of alcohol was calculated 

 and consequently the percentage weight of water. This method gave a result 

 of %0-0'i per cent, as compared witli 20 - 06 by extrapolation of specific gravity 

 of saturated solution. In this way the limits of the isotherm for 20° C, were 

 obtained. Other points on the binodal or boundary cui've shown in fig. 2 

 were found by an experimental method described below. 



A mixture containing a slight excess of n-butyl alcohol over saturation 

 was taken in a long-necked flask of 50 c.c. capacity, fitted with a burette 

 having a long delivery tube reaching almost to the level of the liquid. The 

 flask was immersed in a thermostat, regulated to 20° C. + '005° and acetone 

 run in drop by drop with frequent shaking until the cloudy mixture just 

 became clear on standing. From the increased weight the relative proportions 

 of n-butyl alcohol, acetone, and water were calculated. From a series of these 

 determinations (table II), the boundary curve was plotted both by the com- 

 position and also by the density of the mixture. It will be noted that only 

 a comparatively small percentage of acetone (1'3'4 per cent.) is needed to 

 make n-butyl alcohol and water miscible in all proportions at 20° C. 



Table II. Saturated Solutions of Acetone, n-Butyl Alcohol, and Water. 



