A. Because wood is too _substantial_ to be heated into combustion, by the flame issuing from a mere _match_. Q. _Why would not the paper do as well, if placed on the TOP of the coals?_ A. As every blaze _tends upwards_, if the paper were placed on the _top_ of the fire, its blaze would afford _no contact of flame_ to fuel lying _below_. Q. _Why should COAL be placed ABOVE the wood?_ A. As every flame tends _upwards_, if the wood were _above the coal_, the _flame_ would not rise _through the coal_ to heat it. Q. _Why is a FIRE KINDLED at the LOWEST BAR of a grate?_ A. As every flame tends _upwards_; when a flame is made at the _bottom_ of a fire, it _ascends through the fuel_ and heats it: whereas, if the fire were lighted from the _top_, the flame would _not come into contact_ with the fuel piled below. Q. _Why does COAL make such EXCELLENT FUEL?_ A. Because it is so very _hard_ and _compact_, that it burns away very slowly. Q. _Why will CINDERS become RED HOT, quicker than COALS?_ A. Because they are _more porous_ and _less solid_; and are, therefore, sooner reduced to a state of combustion. Q. _Why will not IRON CINDERS burn?_ A. Iron cinders are _cinders saturated with oxygen_; they are unfit for fuel, because they can imbibe _no more oxygen_, being saturated already. Q. _Why are CINDERS lighter than COALS?_ A. Because their vapour, gases, and volatile parts, have been driven off by _previous combustion_. Q. _Why will not STONES do for fuel, as well as COALS?_ A. Because they contain no _hydrogen_ (or inflammable gas) like coals. Q. _Why will not WET KINDLING light a fire?_ A. 1st--Because the moisture of the wet kindling prevents the _oxygen of the air from getting to the fuel_ to form it into carbonic acid gas: and 2ndly--The heat of the fire is perpetually _drawn off_, by the conversion of _water_ into _steam_. Q. _Why does DRY wood burn BETTER than GREEN?_ A. 1st--Because no heat is _carried away_, by the conversion of _water into steam_: and 2ndly--The pores of dry wood _are filled with air_, which supply the fire with oxygen. Q. _Why do TWO pieces of WOOD burn BETTER than ONE?_ A. 1st--Because they help to entangle the _heat of the passing smoke_, and _throw it on the fuel_: and 2ndly--They help to _entangle the air_ that passes over the fire, and create a kind of _eddy_ or draught. Q. _Why does SALT CRACKLE when thrown into a FIRE?_ A. Salt contains _water_; and the _cracking_ of the salt is owing to the sudden _conversion of the water into steam_. Q. _Why will not wood or paper burn, if they are steeped in a solution of POTASH, phosphate of LIME, or AMMONIA (hartshorn)?_ A. Because any "al'kali" (such as potash) will _arrest the hydrogen_ (as it escapes from the fuel), and prevent its _combination_ with the _oxygen of air_. Q. _What is an al'kali?_ A. The con'verse of an _acid_; as _bitter_ is the con'verse of _sweet_, or _insipid_ the con'verse of _pungent_.