A Guide To The Scientific Knowledge Of Things Familiar Part 18

A. The _hydrogen of the tallow_ combining with the _oxygen of the air_, produce a "watery vapour," which is condensed by the _cold gla.s.s_ held above the flame.

Q. _Why does our hand, held ABOVE a candle, suffer from the heat of the flame so much more, than when it is placed BELOW the flame, or on ONE SIDE of it?_

A. Because the hot gases and air (in their ascent) _come in contact_ with the hand placed _above_ the flame: but when the hand is placed _below_ the flame, or on _one side_, it only feels heat from _radiation_.

Q. _Why is a RUSH LIGHT extinguished so much more quickly than a cotton-wicked candle?_

A. As the _rush_ wick is _smooth_ and _hard_, the _mere motion of the air_ (produced by carrying the candle from one place to another,) is sufficient to sever the flame from the rush.

Q. _Why is it more difficult to blow out a COTTON wick?_

A. The _cotton_ wick is _quite full of small threads_ or filaments, which help to _hold the flame on the wick_, like the roots of a tree.

Q. _Why does an EXTINGUISHER put a candle out?_

A. Because the air in the extinguisher _is soon exhausted of its oxygen_ by the flame: and when there is no _oxygen to support it_, the flame goes out.

Q. _Why does not a candle set fire to a PIECE OF PAPER twisted into an extinguisher, and used as such?_

A. 1st--Because the flame very soon _exhausts the little oxygen_ contained in the paper extinguisher: and

2ndly--The flame invests the _inside of the paper extinguisher_ with _carbonic acid gas_, which prevents it from blazing.

Q. _Why is a LONG WICK never upright?_

A. Because it is bent by its own weight.

Q. _Why is a LONG WICK covered with an EFFLORESCENCE at the top?_

A. The knotty or flowery appearance of the top of a wick arises _from an acc.u.mulation of particles partly separated_, but still loosely hanging to the wick.

Q. _Why is not the END of a long wick BURNT OFF, as it hangs over the flames?_

A. Because the length of the wick so diminishes _the heat of the flame_, that it is not _hot_ enough to burn it off.

Q. _Why do PALMER'S METALLIC WICKS never need SNUFFING?_

A. The wick is divided into two parts, each of which _bends outward_ to the outside of the flame; where the _end is intensely heated_, and _separated_ from the wick by the current of air up the candle.

Q. _Why do common CANDLES require to be SNUFFED?_

A. Because the heat of the flame is _not sufficient to consume the wick_; and the _longer_ the wick grows, the _less heat_ the flame produces.

Q. _Why do WAX CANDLES NEVER need SNUFFING?_

A. The wick of _wax_ candles is made _of very fine thread_, which the heat of the flame is sufficient to consume: but the wick of _tallow_ candles is made _of coa.r.s.e cotton_, which is too substantial to be consumed by the heat of the flame, and must be cut off by _snuffers_.

Q. _Why does a PIN, stuck in a RUSH-LIGHT, EXTINGUISH it?_

A. Because a _pin_ (being a good conductor), _carries away the heat of the flame from the wick_, and prevents the combustion of the tallow.

Q. _What is the SMOKE of a CANDLE?_

A. Solid particles of carbon separated from the wick and tallow, but not consumed.

Q. _Why are SOME particles consumed and not OTHERS?_

A. The _combustion of the carbon_ depends upon its _combining with the oxygen of the air_: but as the outer surface of the flame _prevents the access of air to the interior parts_, therefore much of the carbon of those parts pa.s.ses off in smoke.

Q. _Why do LAMPS SMOKE?_

A. Either because the _wick is cut unevenly_, or else because _it is turned up too high_.

Q. _Why does a LAMP SMOKE when the WICK is cut UNEVENLY?_

A. 1st--Because the _points of the jagged edge_ (being very easily separated from the wick,) _load the flame with more carbon than it can consume_: and

2ndly--As the heat of the flame is _greatly diminished by these bits of wick_, it is unable to consume _even the usual quant.i.ty of smoke_.

Q. _Why does a LAMP SMOKE when the WICK is turned up too HIGH?_

A. Because more carbon is separated from the wick _than can be consumed by the flame_.

Q. _Why do not "Argand burners" smoke?_

A. Because a current of air pa.s.ses through the _middle of the flame_; and therefore the carbon of the _interior_ is consumed, as well as that _in the outer coating of the flame_.

Q. _Why does a LAMP-GLa.s.s DIMINISH the SMOKE of a lamp?_