TAKING THE DENSITY OF VAPOUR OF VOLATILE LIQUIDS. 445 
2. A correction for expansion of the glass tube, which amounts to from -4 
cubic centimeter to 0-1 cubic centimeter. 
Both the barometric column and the mercurial column contained in the gra- 
duated tube were reduced to zero, according to tables given for that purpose in 
Bunsen’s “ Geometry.” The water column occupying the bath was measured in 
millimeters, corrected for temperature, and reduced to mercurial measure. 
A. SERIES OF EXPERIMENTS WITH SLIGHTLY Moist ALCOHOL. 


























Vol. in Cub. 
Ob d vol A 
in Cubic Centi- Temperature C, erasure. in ah eee 
PASISNS: m.m. Pressure. 
Dry Hydrogen, 68:18 GC; 600 52°482 
Dry Hydrogen and Alcohol é ° ; 
Vapour—Observation 1, Ha) Bee es ee aa? 
Dry Hydrogen and Alcohol kjves 0 ; : 
eno Obs, 2, 126-04 84 724°6 91:916 
Pe os Hei 124.28 | 77°5° 720-9 91-840 
ee on ‘seat gh 122-68 70:5 717-9 92-117 
Dry Hydrogen and Alcohol 7 4 
apse “Obs. 5. 120-02 61 712 91-922 



The numbers contained in the last column are obtained from those in the 
other columns, by applying Marriorte’s law, and using the coefficient 00366 for 
the expansion of 1° C. Inspection will show that the pressures are nearly alike 
in the five observations made of hydrogen, mixed with alcohol vapour, whilst the 
temperatures vary 40° C. 
Since the numbers in the last column are almost identical, it follows that the 
coefficient of expansion adopted in their calculation is correct. 
The alcohol in this instance was supposed to have been dry, but subsequent 
examination showed that a small quantity of water had escaped the action of 
the dehydrating agents. The vapour density of this moist alcohol may be found 
by the following calculation. We will take Observation 1 :— 
Cubic cent. 
Vol. of hydrogen + alcohol vapour = 92-189 
Vol. of hydrogen = 62°482 
39-707 
The weight of the alcohol which was introduced was 0775 grm. 
Therefore, 39°707 cub. cent. of alcohol vapour weigh -0775 grm, 
39°707 cubic cent. of air weigh :05137 grm. 
‘0775 
"05137 
VOL. XXII. PART III. 
= 1-508, the vapour density of the moist alcohol. 

