a a 
Le - SS 
by Lavoisier, and analytically by Mr. Smithson 
Tennant. Lavoisier burned carbon in oxygen, 
and obtained carbonic acid from the combustion ; 
and Mr. Tennant passed phosphorus vapour over 
carbonate of lime heated to redness, and found 
that, in consequence of the phosphorus abstract- 
ing the oxygen from the carbonate, and forming 
phosphoric acid, and in consequence of the phos- 
phoric acid thus formed combining with the lime 
to constitute phosphate of lime, the carbon or 
charcoal of the carbonate was deposited, in a se- 
parate state, in the form of a light black powder. 
Carbonic acid is very readily obtained, for the 
purposes of experiment or of separate examina- 
tion, by the action of almost any of the acids 
upon chalk or bruised marble; for almost any 
| other acid, particularly the hydrochloric, the 
nitric, or the sulphuric, rapidly abstracts the 
lime of the carbonate, and allows the carbonic 
acid to escape by effervescence. 
Carbonic acid cannot be made to burn or to 
combine with oxygen; and it will neither main- 
tain combustion nor support respiration, but, on 
the contrary, is both extinctive of flame, and de- 
structive of breathing. So great is its extin- 
guishing power upon combustion, that a mixture 
of one volume of it with four volumes of atmo- 
spheric air will prevent a candle from igniting, or 
extinguish the flame of a candle already burning ; 
and so great is its destructive power upon re- 
spiration, that a quantity of it not quite suffi- 
cient to extinguish the flame of a candle will de- 
prive an animal of sensibility, and a quantity 
just sufficient to extinguish flame will produce 
almost instant death. When air contains a large 
proportion of carbonic acid, it violently contracts 
the glottis, and cannot even enter the lungs ; and 
when it contains only so moderate a proportion 
as to obtain entrance to the lungs, it operates as 
a narcotic poison. A large proportion of car- 
bonic acid in atmospheric air constitutes the 
choke damp of coal mines, deep wells, and brew- 
ers’ vats, which has, in such multitudes of in- 
stances, proved rapidly or instantaneously fatal 
to man; and a comparatively small proportion of 
it, from the combustion of charcoal in rooms, 
crowded respiration in cells or close apartments, 
| and the eremacausis of vegetable matter in fens 
and marshes, constitutes all or most of the poi- 
sonous air which, in so many thousands of in- 
stances, has embittered, shortened, or destroyed 
human life. Yet, though injurious or fatal when 
received into the lungs, it is innocuous and ex- 
hilarating when received, in moderate propor- 
tion, into the stomach. It is held in solution, 
to a greater or less degree, by all fountain and 
river water ; it gives to all such water the agree- 
able gout which distinguishes it from the insi- 
pidity, staleness, and disagreeableness of distilled 
water or of recently boiled water ; it constitutes 
the whole of the sparkling, brisk, and sharply 
| racy property of soda water and of the other 
| aerated waters of the manufacturing chemist ; 
CARBONIC ACID. ° 
and it imparts to cider, ginger beer, ale, porter, 
beer, and brisk champaign, the greater portion 
of the agreeable pungency, which renders them 
so highly relishable, and the loss of which, by 
exposure to the air, occasions them to become 
stale. , ’ . 
Carbonic acid abounds in the waters of many 
mineral springs, such as those of Tunbridge, 
Pyrmont, and Carlsbad; it issues directly from 
the fissures of rocks, caves, and mines, in many 
countries, particularly in the vicinity of vol- 
canoes; it accumulates at the bottom of wells, 
and in the recesses of pits and mines, where de- 
composition of carbonates or of organic substances 
extensively proceeds without free communication 
with the open air; it is evolved in vast volumes 
or in constant streams from stagnant fermenta- 
tions and putrefactions in fens, marshes, and 
close forests; and, in all such situations, it is 
liable to exert a most poisonous power upon the 
local atmosphere, or to form, in the recesses or at 
the surface of the earth, exceedingly noxious 
aerial mixtures. Yet, excepting in such situa- 
tions, it nowhere exists in such quantity as to be, 
in even the slightest degree, detrimental to ani- 
mal health and energy. It rises into the atmo- 
sphere, in enormous aggregate quantities, from 
the combustion of all substances containing car- 
bon, from the eremacausis and the destructive 
fermentation of all vegetable substances, from 
the respiration of all animals, and from the pu- 
trefactive decay of all organic matter; for it is | 
formed, in combustion, by the combination of 
the carbon of the burning body with the oxy- 
gen of the atmosphere,—in eremacausis, by the 
resolution of the whole substance of decay- 
ing vegetables into its elements, and the re- 
combination of these into simpler and more 
attenuated forms,—in destructive fermentation, 
by the loss of oxygen and carbon, during the 
transmutation of one ternate substance into 
another,—in the respiration of animals, by the 
combination of the superfluous carbon of the 
blood with the oxygen of decomposed water, 
or with the oxygen of the atmosphere, or with 
both,—and in the putrefactive decay of all ani- 
mal matter, by a transposition of its elements 
or a disturbance of its attractions, such as in- 
volves the conjoint or simultaneous evolution of 
carbon and oxygen in the form of carbonic acid, 
hydrogen and oxygen in the form of watery va- | 
pour, and hydrogen and nitrogen in the form of 
ammonia. Yet though the quantity of carbonic 
acid constantly poured from these sources into 
the atmosphere is great, and though all carbonic 
acid is heavier than atmospheric air, the propor- | 
tion of it relatively to the other constituents of 
the atmosphere does not experience any observ- 
able variatien from season to season, or from year 
to year, and the relative quantity of it, though 
affected by drought or frost, by light or dark- 
ness, and by luxuriance or sterility, is exactly or 
very nearly the same in the higher regions as in 
