THE CULTIVATOR. 
207 
m 
air; may be combined with water, to which it gives a 
brisk and acidulous taste;(10) is destructive of flame, 
and will occasion the death of animals that are obliged 
to breathe it. (11) 
In what state does carbonic acid exist in nature ? 
Carbonic acid is found in three different states, viz. 
in gas, in mixture, and in chemical combination: it is, 
perhaps, the most abundant of all the native acids.(12) 
What instances are thereof its natural existence in the 
state of gas ? 
It is found in the proportion of about one part by 
measure in every thousand parts of atmospheric air; 
also in caverns and mines where it is called the choke- 
damp.(13) 
What instances are there of carbonic acid being found 
mixed with fluids ? 
It is abundant in Spa-water, and in some other acidu¬ 
lous waters.(14) 
In what substances is carbonic acid found chemically 
Combined ? 
Carbonic acid is found in all parts of the world in 
great plenty, in combination with the alkalies, with 
some metallic oxides, in earths, and in stones; particu¬ 
larly in chalk, limestone and marble.(15) 
What is the effect of the combination of carbonic acid? 
Carbonic acid renders mild and salutary some of the 
most acrid and destructive of all known substances. (16) 
specific gravity it is frequently found at the bottom of mines, 
wells, &c. 
(10) In order to saturate water with this gas, it is neces¬ 
sary to subject it to a considerable degree of pressure. The 
persons who are engaged in making the acidulous soda wa¬ 
ter have peculiar conveniences for this purpose. Cider, 
erry, bottled beer, and other fermented liquors, owe their 
riskness and sparkling to the presence of this gas. 
(11) Carbonic acid has also the property of rendering lime 
soluble in water. As the carbonic acid escapes by exposure 
to the air, the calcareous matter is precipitated from the wa¬ 
ter which held it in solution; whence arise the various earthy 
incrustations found in different parts of the world. Fourcroy 
has very aptly remarked, “ that when natural history was 
less enlightened by chemistry, springs of this kind were called 
petrifying waters, and were by the vulgar reckoned among 
the number of miracles. 
(12) Plants of all kinds give out carbonic acid gas, while 
growing in the shade; but when assisted by the rays of the 
sun, there is reason to think, that the plants have the pow¬ 
er of decomposing this acid; for then the leaves give out 
only oxygen gas. Annates de Chimie, tome xiii. page 318. 
Mons. Saussure has shown, that when vegetables decom¬ 
pose carbonic acid gas, they throw off only half of the oxy¬ 
gen; and that the other half, with the whole of the carbon, 
enters into the composition of the plant. He also says, that 
the leaves absorb oxygen gas in darkness, and emit an equal 
quantity when exposed to the light. If this account of ve¬ 
getation be correct, growing vegetables deteriorate the at¬ 
mosphere in the night, and purify it in the day. The roots, 
wood, and petals perform no inspiration. See Philosophical 
Magazine, vol. xx. page 308. 
(13) The floor of the Grotto del Cane, in Italy, is lower 
than the door, and this hollow is always filled with fixed air, 
which can rise no higher than the threshhold, but there 
flows out like water. It has been a common practice to 
drive dogs into this cavern, where they suffer a temporary 
death for the entertainment of the passengers; but a man 
enters with safety, because his mouth is far above the sur¬ 
face of this deleterious air. From the loss of so many dogs, 
in this cavern, it acquired the name of the Grotto del Cane. 
The lake of Averno, which Virgil supposed to be the en¬ 
trance to the infernal regions, evolves so large a quantity of 
this gas. that birds, flying over it, drop with suffocation.— 
Fatal accidents have happened to persons who have incau¬ 
tiously descended into brewers’ vats and wells, before they 
have been purified from this gas. 
Carbonic acid gas so often occupies the bottoms of wells, 
that workmen ought never to venture into such places with¬ 
out previously letting down a lighted candle. If the candle 
burns they may enter it with safety; if not, a quantity of 
quick-lime should be let down in buckets, and gradually 
sprinkled with water. As the lime slakes, it will absorb the 
carbonic acid gas, and the workmen may afterwards descend 
in safety. 
Fatal accidents often happen from burning charcoal in 
chambers; because wherever charcoal is burned this gas is 
always formed. Workmen have also lost their lives by 
sleeping too near lime-kilns, where this gas is extricated in 
abundance. Whenever persons are discovered in such situa¬ 
tions, or are suffering from the effects of carbonic acid gas, 
the same means should be made use of as are directed by the 
Humane Society in cases of apparent death from drowning: 
or when it can be done without loss of time, atmospheric 
air, or even pure oxygen gas, should be forced into the lungs. 
I have known galvanism sometimes employed in such cases 
with the best effects. 
Dr. Henry has suggested to naturalists, that butterflies and 
other insects, the colours of which it is desirable to preserve, 
for the purpose of cabinet specimens, may be suffocated in 
carbonic acid gas, better than by the common mode of killing 
them with the fumes of sulphur. 
(14) These waters have a pleasant light acidity and brisk¬ 
ness, and sparkle in the glass, like fermented liquors; which 
is well known to be the case with water, when artificially 
impregnated with fixed air. Dr. Percival esteems it highly 
medicinal in pulmonic consumptions, and in malignant fe¬ 
vers. 
By great pressure, water maybe combined with more than 
twice and a half of its own bulk of carbonic acid gas. Such 
waters are considerably more acidulated than those afforded 
by nature, and have much greater medicinal effects. 
(15) Carbonic acid is found combined with alkalies, and 
with several metallic oxides. These combinations are called 
carbonates. 
A cubic inch of marble contains as much carbonic acid in 
combination as would fill a six gallon vessel, when in' the 
state of gas. 
(16) We all know the causticity of pure quick-lime, and 
How is the carbonic acid separated from the alkalies 
and earths ? 
Carbonic acid maybe disengaged by most of the other 
acids; but it is usually separated from alkalies by the 
addition of quick lime, which absorbs this acid, and 
thus is converted into carbonate of lime. (17) 
How is carbonic acid usually procured for chemical 
purposes ? 
Carbonic acid gas may be collected in abundance from 
the surface of fermenting liquors; but it is more com¬ 
monly obtained by pouring sulphuric acid upon a mix¬ 
ture of chalk, or marble and water. 
How do you account for the production of carbonic 
acid gas in the process of fermentation. 
In all vinous fermentations a decomposition of the 
saccharine matter takes place ; and a part of the disen¬ 
gaged oxygen, uniting with a part of the carbon of the 
sugar, forms carbonic acid. A decomposition also of a 
part of the water of solution perhaps promotes the pro¬ 
cess. 
What is the cause of vinous fermentation ? 
The cause of vinous fermentation is not well under¬ 
stood ; though it is a process which nature employs and 
which art can imitate, for the decomposition of certain 
vegetable substances,(18) (when in favorable circum¬ 
stances of temperature and solution,) and also for their 
recomposition to form new products. 
What circumstances are necessary to produce vinous 
fermentation ? 
The presence of vegetable matters, of water, of su¬ 
gar, (19) a certain degree of heat, and free escape for 
the carbonic acid as it is generated.(20) 
Can you at all account for the change which is effected 
in saccharine liquors by fermentation ? 
By the process of fermentation the sugar, which is a 
vegetable oxide,(21) parts with a portion of its oxygen 
to form carbonic acid, and becomes converted into alco- 
hol(22) by being thus partially deoxidized. 
Does sugar then become spirit of wine, or alcohol, 
merely by losing a part of its oxygen ? 
No: it parts with a portion of its carbon at the same 
time, in the form of carbonic acid gas, and a new ar¬ 
rangement of the principles, both of the sugar, and of 
the corrosive qualities of the fixed alkalies; but whenever 
these substances are fully saturated with carbonic acid, the 
fir:it forms mild calcareous earth (or chalk,) and the others 
mild neutral salts, applicable to many purposes of medicine 
and domestic economy. 
(17) Though the alkalies readily part with their carbonic 
acid to caustic calcareous earth, yet they have a great affinity 
to this acid, as may be shown by the following interesting 
experiment,:—-Fill a jar with carbonic acid gas, then pour in¬ 
to it a small quantity of a solution of caustic potash or soda; 
and having tied the mouth over with a wetted bladder, move 
the vessel so as to spread the alkali over its inner surface, 
when a vacuum wall be quickly formed by the absorption of 
the gas, which will appear by the bladder being pressed in¬ 
wards by the weight of the atmosphere. If this experiment 
be made in a glass vessel, its surface will be seen covered 
with crystals of the alkali, as the carbonic acid always pro¬ 
motes the crystallization of the fixed alkalies. 
(18) Fourcroy admits five distinct species of vegetable 
fermentation, viz. the saccharine (or that which forms su¬ 
gar,) the vinous, the acetous, the colouring (or that which 
is developed by the maceration of the indigo plant,) and the 
putrid. See Fourcroy’s System of Chemical Knowledge, vol. 
viii. page 148. Some writers have spoken of another kind 
of vegetable fermentation, viz. the panary, or that which 
manifests itself in making bread; but surely this is a species 
of the acetous, for its tendency to acidify is very evident. 
(19) It appears from several late experiments carefully 
made, that sugar is composed entirely of hydrogen, oxygen 
and carbon. Mr. Cruickshank made many experiments on 
fermentation, and invariably found, that whenever he added 
a fourth substance to the three which compose saccharine 
matter, no fermentation took place. He tried lime, and at 
another time a small quantity of potash; and the addition of 
either prevented fermentation. 
(20) To produce vinous fermentation, it is necessary that 
the matters subjected to that process should be placed in a 
temperature not lower than about 55 degrees of Fahrenheit. 
No kind of fermentation is ever known below the freezing 
point. 
(21) Lavoisier, having analyzed sugar, found that it was 
composed of hydrogen, oxygen and carbon, in the following 
proportions:—Hydrogen 81bs. oxygen 641bs. carbon 281bs. in 
every 100 pounds weight of sugar. Lavoisier’s Elements of 
Chemistry, page 188. Having subjected lOOlbs. of sugar to 
fermentation, he found the products (alcohol, carbonic acid, 
and acetous acid,) when analyzed, contained the precise 
quantities of hydrogen, oxygen and carbon, which were con¬ 
tained in the original sugar. The particular detail which he 
has given of these experiments is extremely interesting. Ibid, 
page 185 to 197. In consequence of the results which were 
obtained, he remarks, “ The effect of the vinous fermenta¬ 
tion upon sugar is thus reduced to the mere separation of its 
elements into two portions: one part is oxygenized at the 
expense of the other, so as to form carbonic acid, while the 
other part being deoxygenized in favor of the former, i# con¬ 
verted into the combustible substance called alcohol.” Ibid, 
page 196. The strongest alcohol of commerce is seldom of a 
less specific gravity than that of 0.825. Proof spirit, or the 
spirit of wine employed in pharmacy, has a specilic gravity 
of 0.93,0. 
(22) Alcohol, according to the analysis of Lavoisier, is 
composed of 
Carbon about - - - 30 parts. 
Hydrogen, - - - - 7.5 parts. 
Water, - - . - - 62.5 parts, 
100.0 
But as this analysis was made by burning alcohol in oxygen 
gas, it is probable that the greater part of the water was 
formed during combustion. Hence the real component parts 
of alcohol are not accurately known. 
the water in which it is dissolved, taking place, furnish¬ 
es an increased proportion of hydrogen, in order to iorm 
vinous liquor. (23) 
Endeavor to recollect the different properties of char¬ 
coal, which you have enumerated in this chapter. 
Charcoal appears to be indestructible by age; it is 
not in the least altered by the most intense heat, if heat¬ 
ed in closed vessels; when burnt in atmospheric air it 
becomes converted into carbonic acid gas; it is a valua¬ 
ble antiseptic; it is the basis of all vegetables; it is 
one of the component parts of wax, oils, gums, and re¬ 
sins; and from its affinity to oxygen it has the property 
of decomposing many substances in which oxygen con¬ 
stitutes a material part. 
How did chemists become acquainted with all these 
properties of charcoal ? 
Formerly, nothing was known of charcoal but its in¬ 
destructibility and its antiseptic qualities. The other 
peculiar and surprising properties of charcoal were re¬ 
served for the discoveries of the present age ; for these 
we are most especially indebted to the labours and gen- 
ious of Black,(24) Priestly,(25) Cavendish, Lavoisier, 
Guyton, Tennant and Berthollet, and to the gradual de¬ 
velopment of the present improved system of chemistry. 
What reflections naturally present themselves on the 
consideration of the various properties of charcoal and 
the other simple combustibles ? 
This subject, when considered in all its connexions, is 
calculated to produce the most profound admiration; 
and serves to convince us of the unbounded compre¬ 
hension of the Divine mind, which, in the act of crea¬ 
tion, could foresee and appoint such important effects to 
result from the combinations and changes of the most 
inodorous and insipid substances. We also learn, that 
all the works of the Creator are perfect; and perceive 
with astonishment, that they are composed of elements 
which are in themselves incapable of destruction. 
(23) The spirituous or intoxicating qualify of all fermented 
liquors is owing to the alcohol they contain, whether it be 
malt-liquor, wine or spirits. Alcohol expands by slight de¬ 
grees of heat more than any other fluid;—hence the proprie¬ 
ty of employing it in forming thermometers. The same de¬ 
gree of heat which expands glass one degree will expand al¬ 
cohol 180 degrees. 
Alcohol has various uses in pharmacy and chemistry. It 
dissolves the resins and volatile oils. Hence its employment 
in the preparation of spirit varnishes. It is employed also in 
chemistry, in separating those salts from each other which 
cannot easily be separated by any other means. It dissolves 
the oxalic, tartaric, and some other acids. The salts which 
are dissolved in the greatest quantity by alcohol are the mu¬ 
riates of magnesia and of lime, and the several nitrates of 
magnesia, lime, alumina, ammonia, and soda. 
(24) In the year 1755, Dr. Black discovered the acid gas 
which is thrown off from fermented liquors and from mild 
calcareous earth. He called it fixed air. 
(25) Dr. Priestly explained the effect of charcoal in de-^ 
composing nitrous acid, examined the gas that is thrown off 
in this decomposition, and pointed out the necessity of dis¬ 
tinguishing the different gases from common air; for which 
the Royal Society awarded him an honorary prize. 
In the years 1766 and 1767, Mr. Cavendish published pa¬ 
pers in the Philosophical Transactions, on the nature of elas¬ 
tic fluids, in winch he announced that he had produced fixed 
air by the burning of charcoal. This assurance called the 
attention of all chemists to that surprising substance, and 
was the forerunner of the many discoveries which have since 
been made respecting its properties, &c. 
Lavoisier pointed out the nature of the action of charcoal 
in reducing metallic oxides; investigated the nature of the 
combustion of the diamond; announced the exact quantity 
of carbon in carbonic acid, and the production of carbonic 
acid by the decomposition of water with ignited charcoal. 
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