M. Mendclejcff on the Compounds of Alcohol with Water. 141 



of water does not materially alter the coefficient of the expansion 

 of alcohol. 



In the fourth chapter, the author endeavours to determine the 

 contraction which ensues when alcohol and water are mixed. 

 For this purpose the specific gravity was taken of accurately 

 weighed quantities of absolute alcohol and water free from air, 

 at temperatures of from 0° to 30°. The different mixtures con- 

 tain 40 to 50 per cent, of absolute alcohol. The observations 

 were interpolated by means of the method of least squares. 

 From these it follows that the greatest contraction takes place 

 with a mixture which contains 45*88 per cent, of absolute alco- 

 hol. Such a mixture can be expressed very accurately by the 

 formula € 2 H 6 + 3H 2 G, which requires 46 per cent. This 

 mixture exhibits the greatest contraction at all temperatures. 



The author sees in this a direct proof that the mixture 



€ 2 H 6 "0 + 3H 2 O 



represents a more intimate combination of the alcohol with the 

 water. From his observations on the maximum contraction, the 

 following Table is taken. The contraction refers to 100 volumes 

 of the resultant mixture of alcohol and water. 



Percentage 



of absolute 



alcohol. 



Contraction 



at 0°. 



10°. 



15°« 



20°. 



30°. 



40 

 45 

 46 

 47 



50 



4-0666 

 41440 

 4-1461 

 41441 

 41145 



3-8180 

 3-8936 

 3-8956 



3-8937 

 38678 



3-7075 

 3-7821 

 3-7840 

 3-7823 

 3-7581 



36060 

 3-6796 

 3-6815 

 3-6799 

 3-6575 



34306 

 3-5023 

 3-504 1 

 3-5027 

 3-4839 



The author devotes the last chapter to the changes of specific 

 gravity on mixing alcohol with water; and at the same time he 

 tried to find an empirical formula for the dependence of the spe- 

 cific gravity on the composition of the mixture. The mixtures 

 prepared by the author contained 40 to 100 per cent, of abso- 

 lute alcohol. For weaker alcohol only a few observations were 

 made; and for mixtures under 25 per cent., the observations of 

 Gilpin and Drinkwater were used. The observations were all 

 interpolated by the method of least squares. We give the follow- 

 ing Table for the specific gravity of aqueous alcohol : — 



