TAKING THE DENSITY OF VAPOUR OF VOLATILE LIQUIDS. 447 
A correction of 0:4 cub. cent. for air contained in the alcohol bulb has to be 
made. This quantity must be subtracted from the volume of alcohol vapour. 
The vapour densities, as deduced from the three observations, are as follows :— 
Vapour Density. 
Observation 1 at 99° ; 
2. at 83-52 ’ 1-580 
tT 3 antee? 1°592 
The same sample of anhydrous alcohol gave without hydrogen :— 
Weight of the Alcohol taken = ‘0991. 

Vol. in Cubie 
Pressure in Cent. corrected 
Millimeters. at 0° C. and 760 
Millimeters. 
Observed volume 
in Cubic Centi- | Temperature C. 
meters. 





Vol. of Alcohol Vapour— : ae % , 
Ohreevation’ 1: 75°42 100°5 661:9 48024 


Correction for air contained in the bulb = 0:1 c.c. 
; Vapour Density. 
Observation 1 at 100-5° ? ; 1-599 
~~ Dat 865° 1:602 
Here, again, we notice the same peculiarity as in the former experiments with 
the specimens of moist alcohol, viz., the vapour densities taken with hydrogen 
are rather lower than those taken without it. We shall recur to this circumstance 
afterwards. 
The theoretical vapour density of alcohol calculated from the sp. gr. of hydro- 
gen is © x:0691 = 1:5893, a number which agrees with our experiment. 
In several elementary works on organic chemistry, in RecNavutt’s “ Manual” 
for example, the following vapour densities for alcohol at different temperatures 
are given :— 
Temperature. Vapour Density. 
88° C. : ; : , 1:725 
98° : : ; 1-649 
110° 3 : : : 1610 
125° , 5 ; ‘ 1603 
150° : : ’ : 1604 
175° : : : c 1:607 
200° : : 6 5 1:602 
Our observation does not confirm the decrease of ‘08 in density between 88° C. 
and 98° C. Between 86°5° and 100°5", we have an decrease of -003 only. 
