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GAS. 
fjoth prosperous and adverse adventures, 
that having stoutly vanquished thy enemies 
both of body and soul, thou mayest not only 
receive the praise of this transient combat, 
but be crowned with the palm of eternal 
victory.” 
Then the knight elected kisses the Sove- 
reign’s hand, thanks his Majesty for the 
great honour done him, rises up, and salutes 
all the companions severally, who return 
their congratulations. 
GAS. This term was first applied by 
Van Helmont, to denote the permanently 
elastic exhalations afforded in chemical pro- 
cesses. Dr. Priestley, whose extensive and 
successful researches into this department 
of natural philosophy in the space of a few 
years produced a revolution in the science 
of chemistry, used the word air as the gene- 
ric term for permanently elastic fluids. 
Other chemical writers of great reputation 
have thought fit to revive Van Helmont’s 
term, and confine the word air to the atmos- 
pheric fluid. As this has been found con- 
venient, to prevent confusion of ideas, it is 
now generally adopted ; the gases which 
are not fully treated under the articles of 
their respective bases, will properly find a 
place here. 
Gas, ammoniacal. See Ammonia, 
Gas, carbonic acid. This is the first of 
the elastic fluids that appears to have been 
distinguished from common air, though its 
nature was not properly understood till it 
was investigated by Dr. Black. Its deadly 
properties, as it is met with in subterranean 
cavities, particularly the celebrated Grotto 
del Cano near Naples, occasioned it to be 
distinguished by the name of spiritus lethalis. 
Van Helmont first gave the name of gas, 
from a German word equivalent to our spirit, 
to this vapour produced from burning char- 
coal. He likewise called if spiritus sylves- 
tris, and when arising from fermented liquors 
spiritus vinosus. From its existing in the 
inelastic state, in water, it was called fixed 
air, a name which Black and others long re- 
tained ; Bewley termed it mephitic air, from 
its great abundance in nature combined with 
lime in the form of chalk, and it has been 
named the cretaceous and the calcareous 
acid, subsequent to the discovery of its 
acid nature. But carbonic acid has super- 
seded all those, since it appears to have been 
ascertained, that its radical is carbon. Of 
Jhis, or rather of charcoal, according to the 
experiments of Lavoisier, it contains twenty 
eight parts by weight, to seventy-two of 
oxygen. Guyton Morveau considers it as 
composed of 17.88 pure carbon, and 82.12 
of oxygen. 
Carbonic acid gas exceeds every other in 
specific gravity, except the sulphurous. 
Hence the vapour in the Grotto del Cano, 
rises but a little above the surface ; and the 
choak damp of miners, which is this gas, lies 
on the ground. Thus, too, when it is emit- 
ted from a fermenting liquor, it first fills 
the empty portion of the vat, displacing the 
lighter atmospheric air ; and then flows over 
the sides, almost as water would do. For 
the same reason, if a bottle filled with it be 
inverted over the flame of a candle at some 
distance, it will descend, and extinguish it. 
According to the experiments of Mr. Caven- 
dish, one part of this, mixed with nine of 
atmospheric air, renders it incapable of 
supporting combustion. 
From the powerful attraction of carbon 
for oxygen, the base of this gas is not easily 
decomposed; but Mr. Tennant effected it 
by introducing phosphorous into a coated 
glass tube, closed at one end, and over this 
powdered marble. A very small aperture 
only being left in the other end of the tube, 
and a red heat applied for some minutes, 
phosphate of lime and charcoal were found 
in the tube. Dr. Pearson did the same 
with phosphorus and carbonate of soda. 
The carbonic acid gas, is likewise decom- 
posed in part by hydrogen gas, assisted by 
electricity. In a glass tube eight lines in 
diameter, De Saussure exposed a column 
of four inches in height, of carbonic acid 
gas, and three inches of hydrogen gas, over 
mercury, to the action of the electric fluid 
circulating between iron conductors, for 
twelve hours. The gases were at first con- 
densed very rapidly, but by degrees more 
and more slowly, till in this period they were 
reduced to four inches. Of this, one inch 
was absorbed by potash, being carbonic 
acid gas, and the other three were nearly 
pure carbonic oxide, the hydrogen having 
formed water with the oxygen, abstracted 
from the carbonic acid. The mercury and 
the conductors were but very little oxyded. 
De Saussure had previously found, that car- 
bonic acid, and hydrogen gases standing 
together over mercury, for the space of a 
twelvemonth had decreased in volume. 
Gas, carbonic oxide. This gas was first 
made known, by Mr. Cruickshank. Dr. 
Priestley had observed, that, when scales of 
iron mixed with charcoal, or with carbonate 
of barytes, were exposed to a strong heat, 
large quantities of a combustible gas were 
extricated, which he supposed to be heavy 
