GAS. 
procured likewise by treating arsenious 
acid, or arsenic and iron filings, or arsenic 
and tin filings with muriatic acid ; but still 
better by treating four parts of granulated 
zinc and one of arsenic, with sulphuric acid 
diluted with twice its weight of water. 
This gas is insoluble in water; does not 
render lime water turbid ; mixed with atmos- 
pheric air no diminution of bulk ensues, but 
the mixture, when fixed, detonates loudly, 
and deposits metallic arsenic ; it has an alli- 
aceous smell; it extinguishes burning bo- 
dies, and is fetal to animals ; it is decom- 
posed by oxygenated muriatic acid gas. If 
a lighted taper be immersed in a phial of 
this gas, it is instantly extinguished ; but the 
gas burns at the mouth of the phial with "a 
lambent white flame, which diffuses white 
fumes of arsenious acid. If it be inflamed 
in a phial with a small orifice, the flame gra- 
dually descends to the bottom of the phial, 
which becomes coated with crystallized me- 
tallic arsenic. Two parts of this gas, with 
one of oxygen, will explode loudly, and 
the products are water and arsenious acid; 
soap bubbles made with a mixture of these 
• gases, explode with a blueish white flame. 
Equal parts of the gases explode with a 
much more vivid flame, but less noise. A 
stream of this gas, burned in a large re- 
ceiver filled with oxygen, emits a blue flame 
of uncommon splendour. According to 
Tromsdorff’s calculation, a cubic inch of 
the gas contains about a quarter of a grain 
of the arsenic. Its specific gravity is rather 
more than half that of atmospheric air. 
Gas, carburetted hydrogen. There are 
several varieties of this gas, the hydrogen 
holding different proportions of carbon in 
solution, according to the process by which 
it is obtained. 
The gas of stagnant water, which may be 
procured by stirring the mud at the bottom 
with a stick, and collecting the gas, as it 
rises in bubbles, in an inverted bottle, is 
this compound, as is also the fire damp of 
coal mines. The vapour of water passed 
through a tube containing ignited charcoal, 
consists of this gas and carbonic acid, which 
may be separated by agitating the mixture 
with lime diffused in water. The vapour of 
ether, or of alcohol, passed through a red 
hot tube of porcelain, coated with clay, 
affords the same products. If three parts 
of concentrated sulphuric acid, and one of 
alcohol, be distilled in a glass retort with a 
gentle heat, a carburetted hydrogen comes 
over. This is distinguished by the name of 
olefiant gas, from its property of forming an 
oil on coming into contact with oxygenated 
muriatic acid gas. If five measures be 
mixed with six of the oxygenated muriatic 
gas, as rapid a diminution takes place as 
when nitrous and oxygen gases are added 
to each other, and a thin film of oil forms 
on the surface of the water. 
Mr. Henry examined these and some 
other varieties, as well as pure hydrogen, 
with a particular view to the light they 
were capable of affording, and the follow- 
ing are his tabulated results : 
GASES. 
Okygen gas 
required to 
saturate ICC 
measures. 
Measures 
of carbonic 
acid pro- 
duced. 
Pure hydrogen 
50 to 54 
60 
0 
... 35 
Gas from moist charcoal 
*i4 
dried peat.... 
— coal 
68 
... 43 
170 .. 
... loo 
lamp oil 
190 
... 1 94 * 
stagnant water 
wax 
200 
... 100 
<>, 9.0 
1 ^7 
Pure olefiant gas 
284 ... 
The light evolved appeared to be in pro- 
portion to the oxygen consumed, so that tfie 
first four in the list yielded very little ; but 
the last much exceeded all the rest. Its 
detonation with oxygen gas too is more vio- 
lent than that of any other inflammable 
gas, .03 of a cubic inch, with .17 of oxygen 
gas, being sufficient to burst a strong glass 
tube. 
About the year 1792, Mr. Murdoch 
made various experiments on the gas from 
coal, peat, and other substances, as a sub- 
stitute for lamps and candles, both as fixed 
and as moveable lights, and in 1793 he ap- 
plied it to the purpose of lighting the exten- 
sive manufactory at Soho. Light was pro- 
cured by the same means several years ago 
at the ovens in Shropshire, for preparing 
coke and tar on Lord Dundonald’s plant 
And six or seven years since a projector at 
Paris lighted up his house and gardens, and 
proposed to light the streets of the eity in a 
similar way. 
The varieties above enumerated differ in 
specific gravity, the olefiant gas being the 
heaviest, and that from charcoal the light- 
est. They differ likewise in the quantity 
absorbed by water, which takes up one- 
eighth its bulk of olefiant gas, one-sixty- 
