4^2 Mr, Faraday on new compounds 
two hours : a length of time which appears to be quite suffi- 
cient for the removal of any of the peculiar vapours from oil 
or coal gas. 
My mode of operating was generally in glass tubes over 
clean mercury,* introducing the gas, vapour or mixture, and 
then throwing up the sulphuric acid by means of a bent tube 
with a bulb blown in it, passing the acid through the mer- 
cury by the force of the mouth. The following results are 
given as illustrations of the process : 
Oil gas from a gasometer. 
in 8' in 
. i hour. 
2 hours. 
diminution. 
188 vol. + 
9.5 vol. sulphuric acid diminished to 155 
148.5 
146.4 
22.12 per cent. 
107 
+ 
13- 
88.5 
84.5 
82.0 
23-33 
138 
+ 
5.2 - 
113.7 
108.0 
106.5 
22.82 
Oil gas from Gordon’s lamp. 
* 5 ' 
30' 
3 hours. 
214 
+ 
6.8 - 
183.3 
180.8 
176. 
17.75 
159 
+ 
S -9 - 
» 37-5 
136.0 
130.4 
17.98 
II3 
+ 
12.2 
1 
1 
1 
1 
SO 
00 
b 
96.0 
92.0 
18.58 
Coal gas of poor quality. 
548.6 
+ 
27.6 
533-3 
529.2 
529 
3-57 
273.6 
+ 
00 
1 
1 
267.9 
266 
266 
2.78 
190.6 
+ 
131 - 
186. 
00 
184.1 
3.41 
Oil may also be used in a similar manner for the separa- 
tion of these vapours. It condenses about 6 volumes of the 
most elastic vapour at common temperatures, and it dissolves 
with greater facility the vapour of those liquids requiring 
higher temperatures for their ebullition. I found that in 
• If the mercury contain oxidizable metals, the sulphuric acid acts upon it, and 
evolves sulphurous acid gas. It may be cleaned sufficiently by being left in contact 
with sulphuric acid for 24 hours, agitating it frequently at intervals. 
