A. Because vast quant.i.ties of _carbonic acid_ are thrown off by decaying _vegetables_; and (as the wind cannot penetrate the thick brushwood to blow it away) _it settles there_, and destroys animal life.

Q. _Why are PERSONS sometimes KILLED by having a CHARCOAL FIRE in their bed-rooms?_

A. When charcoal is burned, the _carbon of the charcoal_ unites with the _oxygen of the air_, and forms _carbonic acid gas_, which is a narcotic poison.

Q. _Why does the carbonic acid gas of a CHARCOAL FIRE RISE and DISPERSE itself about the room; whereas the carbonic acid gas of a BEER VAT SETTLES near the FLOOR?_

A. The carbonic acid gas of a charcoal fire _is heated_ by the _combustion of the fuel_, and rises; but the carbonic acid gas of a beer vat is _not_ heated, and, therefore, rests on the _bottom of the vat_.

Q. _Why do persons throw LIME into BINS to PREVENT their offensive SMELL, in summer time?_

A. Bins contain large quant.i.ties of _carbonic acid gas_, which readily _combines with lime_, and produces "_carbonate of lime_," which is entirely free from all offensive odour.

Q. _Why do persons throw LIME into SEWERS in summer time?_

A. Sewers (like bins) contain large quant.i.ties of _carbonic acid_, which readily _combines with lime_, and produces _carbonate of lime_; and thus the offensive gas of the sewer is neutralized.

Q. _Can carbonic acid be removed in any way BESIDES by LIME?_

A. Yes; _water_ thrown into a pit will disperse the carbonic acid.

Q. _What effect has WATER on CARBONIC ACID GAS?_

A. Water (under _pressure_) _absorbs_ carbonic acid gas; and _parts_ with it (when the _pressure is removed_) in the form of EFFERVESCENCE.

Q. _Why does AERATED WATER effervesce, when the CORK is removed?_

A. While the _cork was fastened down_, the water _absorbed_ the carbonic acid; but the moment _the pressure is removed_ (by taking out the cork) the gas is given out with _effervescence_.

Q. _Why does SODA WATER effervesce?_

A. Soda water contains 8 times its own bulk of carbonic acid gas, which makes its escape in _effervescence_, the moment that the _cork is removed_.

Q. _Why does GINGER POP fly about in froth, when the string of the cork is cut?_

A. All vinous fermentation produces carbonic acid gas. While the _cork is fast_, the water of the liquor _absorbs_ the carbonic acid; but the moment that the _pressure is removed_, the gas is given off in _effervescence_.

Q. _Why does BOTTLED ALE froth, more than DRAUGHT ale?_

A. Because the _pressure_ is greater in a _bottle_ than in a tub which is perpetually tapped: and effervescence is always produced _in proportion to the pressure_.

Q. _Why does bottled ALE and PORTER become "LIVELY" and FROTHY by being SET before the FIRE?_

A. The heat of the fire _expands the air_ (between the liquid and the cork), and as this air expands, _it presses the liquid down_, which causes effervescence.

Q. _What produces the FROTH of BOTTLED PORTER?_

A. The _carbonic acid gas_, produced by its _vinous fermentation_; which is _absorbed by the liquor_ so long as the bottle is _well corked_, but is _given off in froth_ as soon as the pressure of the cork is _removed_.

Q. _What gives the pleasant ACID taste to soda water, ginger beer, champagne, and cider?_

A. The presence of _carbonic acid_, generated by fermentation, and liberated by effervescence when the pressure of the cork is removed.

Q. _Why does fresh SPRING WATER SPARKLE, when poured from one vessel to another?_

A. Because fresh spring and pump water contain _carbonic acid_; and it is the presence of this gas _which makes the water sparkle_.

Q. _What is the FERMENTATION of BEER and WINE?_

A. The production of carbonic acid gas and al'cohol.

Q. _How is CARBONIC ACID GAS produced by FERMENTATION?_

A. Malt and fruit _both contain sugar_; and sugar consists of carbon, oxygen, and hydrogen. In fermentation, a part of the _carbon and oxygen_ of the sugar escape, _in the form of carbonic acid gas_.

Carbonic acid gas is a compound of carbon and oxygen, in the following proportions:--3 lbs. of carbon and 8 lbs. of oxygen will form 11 lbs. of carbonic acid gas. Now, 100 lbs. of white sugar contains 43 lbs. of carbon; 50 lbs. of oxygen; and 7 lbs. of hydrogen.

Q. _How is AL'COHOL produced by FERMENTATION?_

A. The _hydrogen of the sugar_ combines with the _residue of the oxygen and carbon_ to form "AL'COHOL."

Q. _What is AL'COHOL?_

A. Al'cohol is the _spirit_ of wine or beer, obtained by _fermentation_.

(100 gallons of alcohol consist of 38 gallons of oxygen; 43-1/2 of carbon; 15 of hydrogen; and 3-1/2 of nitrogen.)