OF THE PARAFFINS AND THEIR MONOHALOGEN DERIVATIVES. 
19 
of the absence of air to use the liquefied gas. This was done in the remaining 
experiments. 
The gas on issuing from the apparatus in which it was prepared, was passed 
through potash solution and sulphuric acid, and was then condensed in a glass tube 
standing in a freezing mixture of ether and solid carbonic acid. Pa,rt was then 
redistilled into the apparatus shown in fig. 5, which was also used in a similar 
manner in the propane experiments. 
A. is the tube in which the methyl chloride was collected on its evolution from the 
apparatus in which it was prepared. 
The condenser X consisted of two beakers, one inside the other, with a large 
boiling tube suspended in the inner one by the wooden cover. This tube contained the 
freezing mixture, and in it was the small test-tube C, closed air-tight by a stopper 
through which passed two glass tubes, one of them reaching to the bottom. 
F being closed and B and E open, the liquid in A evaporated off quite slowly 
in consequence of the cooling produced by this operation, and passing through G, 
which contained soda-lime, and H, which contained sulphuric acid, was condensed in 
C, anything remaining uncondensed passing into the air at E. When the tube C 
was almost full B was closed, and the tube of methyl chloride taken out of the 
freezing mixture, which caused it to evaporate and drive out the air from above it. 
When this evaporation had gone on for a short time, E was closed and F opened, 
admitting the vapour into the Kundt apparatus. 
Four determinations of the vapour density gave the following results, the pressure 
and temperature being recorded in each case. 
C; 
Table III. 
p- 
f. 
!>■ 
382 
14-6 
I'754 
602 
12-6 
1702 
5.33 
13-9 
17.59 
660 
13-5 
1765 
In the experiments the pressures were read to *05 millim. In this and all the 
following tables I have given them to the nearest millimetre. 
The numbers in the third column are the specific gravities of the gas referred to 
air at the same temperature and j^ressure. 
These values are plotted in fig. 6, and from the curve the values of the density are 
taken for the pressures at which the velocity of sound experiments were made. 
To find the correction factor 1 / p . d[pv) / dv, the following method was adopted :— 
Taking the reciprocals of the densities given in Table III., we get values of pv in arbi- 
D 2 
