Part 10 (1/2)
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 pa.s.sing smoke_, and _throw it on the fuel_: and
2ndly--They help to _entangle the air_ that pa.s.ses 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_.
Q. _Why does a JET of FLAME sometimes burst into the room THROUGH THE BARS OF A STOVE?_
A. The iron bars conduct heat to the _interior of some lump of coal:_ and its volatile gas (bursting through the weakest part) is kindled by the glowing coals over which it pa.s.ses.