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<h2>CHAPTER XIII.</h2> <hr class="bible-verse" /> "Neither do men light a candle, and put it under a bushel, but on a candlestick; and it giveth light unto all that are in the house."—Matt. v. <hr class="bible-verse" /> 244. Why will a piece of paper, held three or four inches over the flame of a candle, become scorched? [Pg 68] Because the hot air and gas produced by the burning of the candle ascends rapidly. 245. Why will a piece of paper held about an inch below the flame of a candle scarcely become warmed? Because the heat ascends; and only a little of it falls upon the paper, and that by radiation. <div class="figright"> <ANTIMG src="images/i-068.jpg" width-obs="183" height-obs="400" alt="" /> <div class="caption">Fig. 2.—DIAGRAM SHOWING THE COMBUSTION OF A CANDLE.</div> </div> 246. Why does the lower part of the flame of a candle (D) burn of a blue colour? Because the hydrogen of the tallow, having a stronger affinity for the oxygen of the air than carbon has, ignites first. Pure hydrogen burns with a bluish flame. 247. Why does the middle of the flame (C) look dark? Because it is occupied with gaseous vapours, derived from the tallow, which have not yet ignited. 248. Why does the upper part of the flame (B) produce a bright yellow light? Because it is in this part of the flame that the hydrogen of the candle, and the oxygen of the air, combine, and there is just sufficient carbon mixed with the hydrogen to improve its illuminating power. 249. Why is there a fringe of pale light (A) around the upper part of the flame? Because some of the carbon escapes in a state of incandesence, and as soon as it reaches the air it combines with oxygen, and so forms carbonic acid gas. [Pg 69] If any dark body, such as the blade of a knife, be held between the eye and the flame of the candle, so as to shut off the light of the more luminous part, the pale fringe around the flame will be found distinctly perceptible. Incandesence means heated to whiteness. <hr class="bible-verse" /> "How oft is the candle of the wicked put out? and how oft cometh their destruction upon them?"—Job xxi. <hr class="bible-verse" /> 250. Why does the flame terminate in a point? Because cold air rushes towards the flame in every direction, and is carried upward. At the point where the flame terminates the cold currents have so reduced the temperature that combustion can no longer be sustained. 251. Why, if you hold anything immediately over the flame, will the flame lengthen? Because, by preventing the rapid escape of the heated air, you maintain a temperature which increases the combustion at the point of the flame. 252. Why should persons whose clothes take fire, throw themselves down? Because flame spreads most rapidly in an upward direction. 253. Why should persons whose clothes are on fire roll slowly about when they are down? Because they thereby press out the fire. 254. Why does pressing a flame or a spark put it out? Because it prevents the contact of the flame or spark with the oxygen of the air. Extinguishers put out the flame of candles in the same manner. A person dies from "suffocation" through the absence of oxygen; and it is literally practicable to "suffocate" a fire. 255. Why does the wick turn black as it burns? Because it consists principally of carbon. 256. Why, when the point of the wick turns out and meets the air, does it exhibit a bright spark? Because the carbon of the wick comes into immediate contact with the oxygen of the air. 257. Why does holding a candle "upside down" put it out? [Pg 70] Because the melted grease runs down too rapidly, and at too low a temperature to undergo combustion. It therefore reduces the heat, and extinguishes the flame. <hr class="bible-verse" /> "Lord, what is man that thou takest knowledge of him! or the son of man, that thou makest account of him."—Psalms cxliv. <hr class="bible-verse" /> 258. Why is it more difficult to blow out the flame of a candle with a cotton wick than one with a rush wick? Because the cotton wick imbibes more of the combustible materials, and holds in its loose texture the inflammable gases in a state ready for combustion. 259. Why does blowing sharply at a candle flame put it out? Because the breath drives away the vapour of the grease which, becoming gaseous, supports the flame. And because too rapid a flow of cold air reduces the temperature below the point at which combustion can be maintained. 260. Why will a gentle puff of breath, if given speedily after the flame is extinguished, rekindle it? Because the oxygen of the air combines with the carbon and hydrogen that are still escaping from the heated wick, and re-lights it. 261. Why will not a similar puff rekindle the flame of a rushlight? Because its wick retains but little heat, and holds a comparatively small amount of combustible matter in a volatile state. 262. Why is a fire, when it is very low, sometimes put out by blowing it? Because the too rapid flow of cold air reduces the temperature of the burning mass. 263. Why will a piece of paper twisted like an extinguisher put out a candle? Because, before the flame of the candle can ignite the paper, the oxygen contained within it is consumed, and the flame is suffocated. [Pg 71] <hr class="bible-verse" /> "When his candle shined upon my head, and when by his light I walked through darkness."—Job xxix. <hr class="bible-verse" /> 264. Why do tallow candles require snuffing? Because the oxygen of the air cannot reach the wick through the body of flame—therefore the unconsumed carbon accumulates upon the wick. 265. Why do composite and wax candles not require snuffing? Because their wicks are made by a series of plaits, by which they are bent to meet the oxygen of the air, and consumed. 266. Why does setting a glass upon a lamp increase its brilliancy, though it shortens the flame? Because it conducts an increase of air to the flame, and the greater supply of oxygen causes the escaping vapour of oil to be all rapidly consumed. 267. Why does a candle burn dimly when the wick has become loaded with carbon? Because the carbon radiates the heat, and disperses it, and reduces the heat of the flame below that temperature which is essential to its luminosity. 268. What differences characterise the combustion of carbon and of hydrogen? The combustion of carbon takes place without the production of flame. The charcoal (or carbon in any other form) being heated to redness, enters directly into combination with the oxygen of the surrounding air, and the carbonic acid gas, being invisible, passes away unobserved. But in the combustion of hydrogen the heat developed is so intense as to render the gas itself luminous, just as iron may be heated to a red or white heat. 269. What has become of the candle when it has been burnt? It has been resolved partly into carbonic acid gas which, though unperceived, has diffused itself through the surrounding air; and partly into water, which escaped in the form of thin vapour. 270. Has any part of the candle been consumed or lost? [Pg 72] No; there is no such thing as "loss" in the operations of nature. Every particle of the candle, now invisible, exists either in the form of gas, vapour, or water, with, perhaps, a few solid particles that may be called ashes, but which are too minute to excite attention. <hr class="bible-verse" /> "I know that whatsoever God doeth, it shall be for ever: nothing can be put to it, nor anything taken from it; and God doeth it that men should fear before him."—Eccles. iii. <hr class="bible-verse" /> The economy of nature should teach us a very impressive lesson—nothing is suffered to be wasted, not even the slightest atom. As soon as any body has fulfilled its purpose in one state of being, it is passed on to another. The candle, existing no longer as a candle, is flying upon the wings of the air as carbonic acid gas, and as water. These probably find their way to the garden or the field, where the carbonic acid gas forms the food of the plant, and the water affords it a refreshing drink. And can it be supposed that the Almighty Being, who has thus economised the existence of the material creation, should be less mindful of the immaterial soul of man? There is an eternity before us, the certainty of which is evidenced even by the laws of the material creation. <hr class="chap" /> <div style="break-after:column;"></div>

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