33 
stream of water. A dog, or any other ani- 
mal, is immediately killed, if its nose is 
thrust into the lower part of the cavern. But 
the upper part of the cavern is quite free 
from the gas, as it does not rise high enough 
to mix with the atmospheric air. 
Carbonic acid gas is likewise formed during 
fermentation. On account of its great weight, 
it occupies the empty space of the vessel in 
which the fermenting process is going on. It 
may, in this case, be collected by plunging a 
vessel into it. 
Light carbonated hydrogen gas, 
is hydrogen gas holding in solution carbon or 
charcoal. There are several kinds of it obtain- 
ed by different processes, which differ in their 
properties, and in the proportions of their con- 
stituent principles. 
Light carbonated hydrogen gas has a disa- 
greeable smell. It is neither absorbed nor al- 
tered by water. It is very inflammable, anti 
burns with a denser and deeper coloured flame 
than pure hydrogen gas. Its specific gravity is 
greater than that of hydrogen gas, or of com- 
mon air. 
This gas is produced from animal, veget- 
able, and mineral substances. It is found very 
commonly in marshes and ditches, on the 
surface of putrid water, in burying-places, 
common sewers, and in those situations where 
putrid animal and vegetable matters are ac- 
cumulated. It is also generated in the in- 
testinal canal of living animals. 
It may be plentifully obtained from most 
stagnated waters. To do this, till a wide- 
mouthed bottle with water, and keep it 
inverted with a funnel in its neck : then 
stir the mud with a stick at the bottom just 
under the funnel, so as to collect the bubbles 
of air which rise in various places : as soon as 
the bottle is tilled with gas, it must be corked 
under water. 
It may also be obtained during the distilla- 
tion of animal and vegetable matters. Let 
shavings of wood or saw-dust be put into a 
retort, and apply a gradual heat till the retort 
becomes red-hot: a great quantity of gas will 
be disengaged, which may he collected over 
water. On examining this gas, it will be 
found to consist of carbonic acid gas and car- 
bonated hydrogen gas. In order to obtain 
the latter in a pure state, the whole must be 
mixed with lime-water, or with caustic alkali 
dissolved in water. The carbonic acid gas 
will be absorbed, and the carbonated hydro- 
gen gas left behind. 
Heavy carbonated hydrogen gas 
is not absorbed by water. It has an odour 
different from that of light carbonated hydro- 
gen gas. It burns with a strong flame, simi- 
lar to that of a resinous oil. When mixed 
with oxygenated muriatic acid gas, its bulk is 
diminished, and oil is formed. 'When the 
mixture of these two gases is exploded, a 
quantity of charcoal is immediately deposited 
in the form of fine soot. When burned with 
oxygen gas, or when passed through a red- 
hot tube tilled with any oxyd from which 
oxygen is procured, carbonic acid gas is 
formed. 
This gas is obtained by decomposing spirit 
of wine, by sulphuric acid in a great heat. It 
is also obtained abundantly, when alcohol is 
passed through a red-hot earthen tube. Sul- 
phuric ether, mixed with sulphuric acid, and 
subjected to heat, also affords it. 
. Let four parts of sulphuric acid, and one of ! 
VOL. I. 
A I ft 
highly rectified ardent spirit, be mingled to- 
gether gradually in a glass retort: heat will be 
disengaged, the mixture will become brown, 
and heavy carbonated hydrogen gas will be 
extricated. When heat is applied, the action 
is very violent, and the gas is procured very 
copiously, and may be received over water. 
The gas so obtained is mixed with a consi- 
derable quantity of sulphureous acid gas, 
from which it may be freed, by agitating it 
with lime-water, or a solution of potash. 
Sulphurated hydrogen gas has the 
properties of an acid ; for when absorbed by 
water, its solution reddens vegetable blues. 
It combines also with alkalis, earths, and with 
several metallic oxyds. Sulphurated hydro- 
gen gas has an extremely offensive odour, 
resembling that of putrid eggs. It kills ani- 
mals, and extinguishes burning bodies. 
When mixed with oxygen gas, or atmosphe- 
ric air, it is inflammable. 
To obtain it, take dry sulpliuret of potash, 
put it into a tubulated retort in a sand-bath ; 
or, supported over a lamp, direct the neck 
of the retort under the receiver placed in 
a pneumatic trough ; then pour gradually 
upon the sylphuret diluted sulphuric acid : a 
violent effervescence will take place, and sul- 
phurated hydrogen gas will be disengaged. 
When no more gas is produced, apply heat 
by degrees till it boils, and gas will again be 
procured abundantly. 
The water employed for receiving it 
should be heated to about 80 or 90 degrees : 
at this temperature it dissolves little of the 
gas ; whereas, if cold water is used, a vast 
quantity of it is absorbed. 
Water impregnated with sulphurated hy- 
drogen gas, slightly reddens blue vegetable 
colours. 
It is this gas which gives to the mineral 
waters of Ilarrowgate and Aix-la-Chapelle 
their peculiar smell. Such waters may there- 
fore be artificially imitated, by impregnating 
common water with this gas, and adding the 
other constituent parts to it. 
This gas acts strongly on most metallic 
oxyds. 
Dip a slip of paper into a solution of lead, 
and expose it to the action of sulphurated 
hydrogen gas; and the paper will instantly 
become blackened. Writing performed with 
this solution is invisible when dry, but be- 
comes visible when immersed in a bottle filled 
with this gas. 
In this instance, the hydrogen of the gas 
takes the oxygen from these bodies, and 
causes them to re-approach the metallic 
state ; at the same time, the sulphur contain- 
ed in the gas combines with the metal thus 
regenerated, and converts it into a sulphuret. 
Phosphorated hydrogen gas consists 
of phosphorus dissolved in hydrogen gas. 
It is the most combustible substance in na- 
ture. It is distinguished from all other gases 
by the property of taking fire immediately 
when brought in contact with atmospheric 
air. When mixed with oxygen gas, or with 
oxygenated muriatic acid gas, it burns witli 
great violence. When bubbles of it are suf- 
fered to pass through water, they take fire in 
succession as they reach the surface of the 
fluid. It has an insupportable odour, similar 
to that of putrid fish. 
To obtain it, take a small retort, put into it 
one part of phosphorus and ten of concentrat- 
ed solution of potash; make the mixture 
E 
boil, and receive the gas over mercury, or, 
if it is intended for iimnediate use, it may be 
collected over water. In this process a de- 
composition of the water takes place. Its 
oxygen unites to part of the phosphorus, 
forming phosphoric acid, which joins to the 
potash, and forms phosphate of potash. The 
hydrogen of the water dissolves another part 
of the phosphorus, and is converted into 
phosphorated hydrogen gas. 
In preparing this gas the body of the retort 
should be tilled as nearly as possible with the 
mixture, otherwise the first portion of gas 
which is produced inflames in the retort, a 
vacuum is formed, and the water is forced up 
into the retort, which endangers the bursting 
of it. 
Phosphorated hydrogen gas is also formed 
by nature. The air which burns at the sur- 
face of certain springs, and forms what is 
called burning springs, and the ignis fatuus 
(jack o’lantern), which glides along burying- 
grounds, consist of this gas. 
If the bubbles of air which come from the 
retort are suffered to escape into the atmo- 
sphere, they w ill burst with a slight explosion, 
and produce flashes of fire. A circular dense 
white smoke rises like a ring, enlarging itself 
continually in an extremely beautiful manner, 
if the air is perfectly tranquil. 
This gas burns with a green light, in nas- 
cent oxygenated muriatic acid gas, under the 
surface ot w ater. Put into a deep glass some 
phosphoretof lime, broken into pieces of the 
size of a pea, and add half as much oxyge- 
nated muriate of potash. Fill the vessel with 
water, and bring into contact with the mate- 
rials at the bottom of the fluid some concen- 
trated sulphuric acid. This may be most 
conveniently done, by letting the acid fall 
through a long funnel reaching to the bottom 
of the vessel. As soon as the decomposition, 
of the w ater, and that of the oxygenated mu- 
riate takes place, flashes of lire dart from the 
fluid, and illuminate the bottom of the vessel 
with a beautiful green light. 
A ribbon, impregnated with a solution of 
gold, may be gilt by the action of phospho- 
rated hydrogen gas. 
Nitrous gas. This name is given to an 
aeriform fluid, consisting of a certain quan- 
tity of nitrogen gas and oxygen; first de- 
scribed by Priestley, but in some measure 
known before to Hales. 
It is colourless, having no sensible taste, 
and is neither acid nor alkaline : it cannot be 
respired. The greater number of combusti- 
ble bodies cannot burn in it. It is neverthe- 
less capable of supporting the combustion of 
some bodies. Phosphorus burns in it, when 
introduced in a state of inflammation; pyro- 
phorus takes fire in it spontaneously. 
To obtain it, put into a small retort some 
pieces of copper, and pour on them nitric acid 
diluted with water; an effervescence takes 
place, and nitrous gas will be produced. After 
having suffered the gas to escape for a few 
minutes, on account of the common air con- 
tained in the retort, collect the gas in the w a- 
ter apparatus as usual. In order to obtain 
this gas in a pure state, it should be shaken 
for some time in contact with water. 
We have seen before, that water was de- 
composed on bringing in contact with it a 
metal and an acid. But here the case is dif- 
ferent ; the water suffers no alteration ; on 
the contrary, the acid undergoes a partial de- 
