A. Because they compel the air to go _through_ the fire, and not _over_ it; therefore the fire is well supplied with oxygen, and the draught greatly increased. Q. _Why does a tin BLOWER INCREASE the DRAUGHT?_ A. As all the air which enters the chimney has to pass _through_ the fire, it is much hotter, and ascends the chimney very fast; and the faster the air _flies up the chimney_, the faster it rushes _towards the fire_ also. Q. _Why does a parlour often SMELL disagreeably of SOOT in SUMMER-TIME?_ A. The air in the _chimney_ (being _colder_ than the air in the _parlour_) _descends into the room_, and leaves a disagreeable smell of soot behind. Q. _Why are the CEILINGS of PUBLIC OFFICES so BLACK and filthy?_ A. The heated air ascending, carries the dust and fine soot to the ceiling; where the hot _air_ escapes through the plaster, and _leaves the soot and dust_ behind. Q. _Why are SOME parts of the ceiling BLACKER and more filthy than others?_ A. As the air cannot penetrate the thick _joists_ of the ceiling, _it passes by those parts_, and deposits its soot and dust on those which are more penetrable. Q. _What is CHARCOAL?_ A. Wood which has been exposed to a red heat, till it has been deprived of all its gases and volatile parts. Q. _Why is a CHARCOAL FIRE hotter than a wood fire?_ A. Because so large a quantity of _water_ has been abstracted from the fuel, by the red heat to which it has been already exposed. Q. _Why does charcoal REMOVE the TAINT of meat?_ A. Because it absorbs all odoriferous effluvia, whether they arise from putrefying animal or vegetable matter. Q. _Why is WATER PURIFIED by being filtered through charcoal?_ A. Charcoal absorbs the _impurities_ of the water, and removes all disagreeable tastes and smells, whether they arise from animal or vegetable matter. Q. _Why are water and wine CASKS CHARRED inside?_ A. _Charring_ the inside of the cask reduces it to a _kind of charcoal_; and charcoal (by absorbing animal and vegetable impurities) keeps the liquor sweet and good. Q. _Why does a piece of BURNT BREAD, steeped in impure WATER, make it fit to drink?_ A. The surface of the bread is reduced to _charcoal_ by being burnt; and the charcoal surface of the bread _abstracts all the impurities of the water_, and makes it palatable. Q. _Why should the TOAST and WATER, placed by the side of the sick, be made of BURNT BREAD?_ A. The surface of the bread being _reduced to charcoal_ by being burnt, prevents the water from being affected by the impurities of the sick room. Q. _Why are TIMBERS, which are to be exposed to damp, CHARRED?_ A. _Charcoal undergoes no change_ by exposure to air and water; therefore timber will resist weather _much longer_, after it has been charred. CHAPTER V. LAMPS AND CANDLES. Q. _Of what are OIL, TALLOW, and WAX composed?_ A. Principally of carbon and hydrogen gas. The _solid_ part is carbon, the _volatile_ part is gas. Q. _What is CARBON?_