PRESENT STATE OF THE CHEMISTRY OF CAS-LIGIITING. 
327 
■cohol radicals, as they are sometimes called, which occupy au intermediate place between 
the marsh gas and the olefiant gas series of compounds. You will here see how in each 
series the proportions of carbon and hydrogen progressively increase in the same volume 
of gas or vapour, and how also the specific gravity of the gas likewise increases; and so 
also does its illuminating power, and its vitiating effect on the atmosphere. In this last 
respect, I have considered that 4 per cent, of carbonic acid in the air renders it irrespir- 
able. You will also note the proportions in which the several compounds are absorbed 
by water. 
Constituents of Coal Gas and their Allies. 
Name. 
c< . 
O CC 
o S 
£ 
1 Volume 
contains 
c$ cn • 
u cg £ 
3 0 S 
OVi ft 
= ° ( G 
Weight of a 
Cubic Foot 
(Grains). 
V olumes 
Soluble in 
100 Vols. of I 
Water. 
c O 
w 4-> 
m 
D « C 
6 Hrh 
Product of 
1 Volume. 
O o ; 
co O 
0Q 
Vol. 
C. 
Vol. 
H. 
O fc-.r* 
c 
o 
p>o 
Vol. 
CC) 2 . 
Vol. 
HO. 
p i- 1—11 
”o * F- 
Marsh 
:gas series 3 
Hydrogen. . . 
Carbonic oxide. 
Methyl hydride 
Ethyl-hydride . 
Propyl-hydride 
Butyl-hydride . 
Amyl-hydride . 
(Methyl . . . 
Ethyl .... 
Propyl . . . 
Butyl .... 
1 Amyl .... 
' Methylene . . 
Ethylene. . . 
Propylene . . 
Butylene. . . 
- Amylene. . . 
Acetylene . . 
Benzole . . . 
| Toluole . . . 
I Xylole . . . 
x Cumole . . . 
I Cymole . . . 
\Napbthalin . . 
H 
C 0 
Co h 4 
c; h„ 
c 0 H s 
C 8 H 10 
C 10 H 12 
c 2 h 3 
o-o 
0-5 
0-5 
\i 
2-0 
2-6 
1-0 
1-0 
0-5(0) 
2-0 
30 
4-0 
50 
6*0 
30 
0-0G9 
0-967 
0-553 
1-037 
1- 520 
2- 004 
2-488 
1-037 
37-1 
519-2 
296-9 
556"8 
816-2 
1076-1 
1336-0 
556-8 
1- 93 
2- 43 
3- 91 
0-50 
o-oo 
o-oo 
0-00 
5-08 
0-5 
0-5 
2-0 
3-5 
5-0 
6"5 
8-0 
3-5 
0 
1 
1 
2 
O 
O 
4 
5 
o 
1 
2 
o 
O 
4 
5 
6 
o 
O 
2-5 
27'5 
35-0 
67-5 
100-0 
132-5 
165-0 
67-5 
c\ h 3 
2-0 
5-0 
2-004 
1076-1 
2-15 
6-5 
4 
5 
130-0 
Alcohol 
c 0 h 7 
3-0 
7-0 
2-971 
1595-3 
0-00 
9-5 
6 
7 
197-5 
radicals . 'i 
c 8 
4-0 
9-0 
3-939 
2115-1 
0-00 
12-5 
8 
9 
262*5 
G t o H11 
5-0 
11-0 
4-906 
2634-3 
0-00 
15-5 
10 
11 
327-5 
Co h 3 
0-5 
1*0 
0-485 
260-4 
0-00 
1-5 
1 
1 
32-5 
c 4 H 4 
1-0 
2-0 
0-970 
520-8 
16-15 
8*0 
O 
fj 
2 
65"0 
'Olefiant J 
C B H„ 
1-5 
3-0 
1"455 
78P2 
0-00 
4-5 
o 
O 
3 
97-5 
gas series. j 
c s FIs 
2-0 
4-0 
1-940 
1041-6 
0-25 
60 
4 
4 
130-0 
G io V io 
C 4 H 2 
2-5 
TO 
5-0 
1-0 
2-425 
0-898 
1302-0 
482-2 
0-00 
100-00 
7-5 
2-5 
5 
o 
5 
1 
162-5 
62-5 
G\oH 0 
3-0 
3-0 
2-695 
1471-3 
0-80 
7-5 
6 
o 
O 
187-5 
c 14 h„ 
3*5 
4-0 
3-179 
1707-0 
o-oo 
9-0 
7 
4 
220-0 
.Benzole 
series. . . 
Ci 0 FIio 
c 1s h 12 
CaoHli 
4- 0 
4'5 
5- 0 
5- 0 
6- 0 
7-0 
3- 662 
4- 146 
4-630 
1996-3 
22*20*2 
2488-1 
0-00 
0-00 
o-oo 
10-5 
12-0 
13-5 
8 
9 
10 
5 
6 
7 
252-5 
215-0 
317-5 
C 20 Hh 
5-0 
4-0 
4-422 
2374-4 
o-oo 
12-0 
10 
4 
311-0 
3. Impurities, or Objectionable Constituents of Coal Gas. 
'These are Carbonic Acid, Oxygen, Nitrogen, Ammonia, Sulphide of Carbon, Sulpho- 
hydrocarbons, Sulphuretted Hydrogen, Cyanogen, and Aqueous Vapour. 
(a) Carbonic Acid (COo). —This gas is always produced in the retorts during the 
narly stages of the carbonization of coal; and if the coals are very wet the quantity of 
the gas is increased by the action of the red-hot coke on the aqueous vapour—hydrogen 
and carbonic acid being produced. The amount of the gas is also augmented if the ex¬ 
hauster draws air through the pores or fissures of clay retorts. This gas consists of car¬ 
bon and oxygen in such proportions that a volume of it contains half a volume of carbon 
vapour and a volume of oxygen. The gas is heavier than air in the proportion of 15202 
to 1; and it is not only incombustible, but it also checks the combustion of other gases. 
A taper is immediately extinguished in air containing 14 per cent, of carbonic acid ; and 
it burns very dimly, and only for a short time, in air containing 12 per cent, of the gas. 
Even detonating gas (a mixture of oxygen and hydrogen in proper proportions) will not 
explode when it is mixed with 2-89, or a little less than three times its volume, of car¬ 
bonic acid. The effect of the gas in reducing the illuminating power of coal gas is very 
marked. You will observe this in the experiment which I will now make. Here is the 
standard flame of the burning gas, and when I introduce about 3 per cent, of carbonic 
acid into the gas, you will notice how seriously the power of the light and the volume 
of the flame are diminished. My own experiments have led me to the conclusion that 
1 per cent, of carbonic acid in common coal gas will diminish the light about 5 per 
cent.; and that 2 per cent, of it in gas will reduce the power of 14-candle gas to about 
12 5. In the case of the jet, a mixture of 5 per cent, carbonic acid reduces the light to 
half. It is, therefore, a serious impurity, and should always be removed from gas. This 
