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CANDLE (Lat. candela, from candere, t...

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Originally appearing in Volume V05, Page 179 of the 1911 Encyclopedia Britannica.
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CANDLE (See also:Lat. candela, from candere, to glow) , a cylindrical See also:rod of solid fatty or waxy See also:matter, enclosing a central fibrous See also:wick, and designed to be burnt for giving See also:light. The See also:oldest materials employed for making candles are beeswax and See also:tallow, while among those of more See also:recent introduction are See also:spermaceti, stearine and See also:paraffin See also:wax. Waxlights (cereus, sc, funs) were known to the See also:Romans. In the midlde ages wax candles were little used, owing to their expense, except for the ceremonies of the See also:church and other religious purposes (see LIG13TS, CEREMONIAL USE OF), but in the 15th See also:century, with the cheapening of wax, they began to find wider employment. The tallow 'candle, mentioned by See also:Apuleius as sebaceus, was See also:long an See also:article of domestic manufacture. The tallow was melted and strained, and then lengths of See also:cotton or See also:flax fibre, or rushes from which most of the See also:external skin had been stripped, only sufficient being See also:left to support the See also:pith (" rushlights"), were dipped into it, the operation being repeated until the desired thickness had been attained. In See also:Paris, in the 13th century, there was a gild of candlemakers who went from See also:house to house to make tallow candles, the manufacture of wax candles being in the hands of another gild. This separation of the two branches of the See also:trade is also exemplified by the existence of two distinct See also:livery companies in the See also:city of London—the Waxchandlers and the Tallowchandlers; the See also:French chandelle properly means tallow candle, candles made of materials less fusible than tallow being called bougies, a See also:term said to be derived from the See also:town of See also:Bougie in See also:Algeria, either because wax was produced there or because the Venetians imported wax candles thence into See also:Europe. The old, 'tallow "dips" gave a poor light, and tallow itself is now used only to a limited extent, except as a source of "stearine.": This is the trade name for a mixture of solid fatty ;acids—mainlystearic and palmitic—manufactured not only from tallow and other See also:animal fats, but also from such See also:vegetable fats as See also:palm-oil. Paraffin wax, a mixture of solid See also:hydrocarbons obtained from crude See also:North See also:American and See also:Rangoon See also:petroleum, and also yielded in large quantities by the Scotch shale oil See also:industry, is, at least in See also:Great See also:Britain, a still more important material of candle-manufacture, which came into use about 1854. Spermaceti, a crystalline fatty substance obtained from the sperm See also:whale (Physeter macrocephalus), was introduced as a material for candles about a century earlier. In practice the candlemaker mostly uses mixtures of these materials.

For instance, 5-10% of stearine, which is used alone for candles that have to be burnt in hot climates, is mixed with paraffin wax, to counteract the tendency to See also:

bend with See also:heat exhibited by the latter substance. Again, the brittleness of spermaceti is corrected by the addition of beeswax, stearine, paraffin wax or ceresin (obtained from the See also:mineral wax ozocerite) . In some "composite" candles stearine is mixed with the hard See also:fat (" See also:cocoa-See also:nut stearine ") expressed from cocoa-nut oil by See also:hydraulic pressure; and this cocoa-nut stearine is also used for See also:night-See also:lights, which are See also:short thick candles with a thin wick, calculated to See also:burn from six to ten See also:hours. The stearine or stearic See also:acid industry originated in the See also:discovery made by M. E. See also:Chevreul about 1815, that fats are glycerides or compounds of See also:glycerin with fatty acids, mostly palmitic, stearic and oleic. The See also:object of the candlemaker is to remove this glycerin, not only because it is a valuable product in itself, but also because it is an objectionable constituent of a candle; the vapours of acrolein formed by its decomposition in the See also:flame are the cause of the unpleasant odours produced by tallow " dips." He also removes the oleic acid, which is liquid at See also:ordinary temperatures, from the palmitic and stearic acids, mixtures of which solidify at temperatures varying from about 130° to 155° F., according to the percentage of each See also:present. Several methods are in use for the decomposition of the fats. In the See also:autoclave See also:process the fat, whether tallow, palm-oil or a mixture of the two, mixed with 25 or 30% of See also:water and about 3 % of See also:lime, is subjected in an autoclave to See also:steam at a pressure of about 120 lb per square See also:inch for eight or ten hours, when nearly all of it is saponified. On See also:standing the product separates into two layers—" sweet water " containing glycerin below, and the fatty acids with a certain amount of lime See also:soap above. The upper layer is then boiled and treated with enough sulphuric acid to decompose the lime soap, the See also:calcium sulphate formed is allowed to subside, and the fatty acids are run off into shallow boxes to be crystallized or " seeded " See also:prior to the separation of the oleic acid, which is effected by pressing the solid blocks from the boxes, first See also:cold and then hot, by hydraulic machinery. In another process saponification is effected by means of concentrated sulphuric acid.

The fat is mixed with 4-6% of the acid and treated with steam in boiling water till the See also:

hydrolysis is See also:complete,when on standing the glycerin and sulphuric acid sink to the bottom and the fatty acids rise to the See also:top. Owing to the darkness of their See also:colour, when this process is employed, the latter usually have to be distilled before being crystallized. The autoclave process yields about 45% of stearine, one-third of which is recovered from the expressed oleic acid, but with sulphuric acid saponification the amount of stearine is higher—over 6o %-and that of oleic acid less, See also:part of it being converted into solid material by the See also:action of the acid. The yield of glycerin is also less. In a See also:combination of the two processes the fat may first be treated by the autoclave process, so as to obtain a full yield (about 10 %) of glycerin, and the resulting fatty acids then subjected to acid saponification, so as to get the higher amount of stearine. At the best, however, some 30% of oleic acid remains, and though often sought, no satisfactory method of converting this See also:residue into solid has been discovered. It constitutes " red oil," and is used in soap-making and in woollen manufacture. In the process patented by See also:Ernst .Twitcheli in 1898, decomposition is effected by boiling the fat with See also:half its bulk of water in presence of a reagent obtained by the action of sulphuric acid on oleic acid and an aromatic See also:hydrocarbon such as See also:benzene. The wick is a most important part of a candle, and unless it is of proper See also:size and texture either too much or too little See also:fuel will be supplied to the flame, and the candle will See also:gutter or be otherwise unsatisfactory. The material generally employed is cotton See also:yarn, plaited or " braided " by machinery, and treated or " pickled " with a See also:solution of boracic acid, ammonium or See also:potassium nitrate, or other See also:salt. The tightness of the plaiting varies with the material used for the candle, wicks for stearine being looser than for paraffin, but tighter than for wax or spermaceti. The plaited wick is See also:flat and curls over as the candle See also:burns, and thus the end is kept projecting into the See also:outer part of the flame where it is consumed, complete See also:combustion being aided by the pickling process it has undergone.

In the old tallow dips the strands of cotton were merely See also:

twisted together, instead of being plaited; wicks made in this way had no determinate See also:bias towards the outside of the flame, and thus were not wholly consumed, the result being that there was See also:apt to be an See also:accumulation of charred matter, which choked the flame unless removed by periodical " snuffing." Four ways of making candles may be distinguished—dipping, pouring, See also:drawing and moulding, the last being that most commonly employed. Dipping is essentially the same as the domestic process already described, but the See also:rate of See also:production is increased by mounting a number of wicks in a See also:series of frames, each of which in turn is brought over the tallow See also:bath so that its wicks can be dipped. Pouring, used in the See also:case of wax, which cannot well be moulded because it contracts in cooling• and also has a tendency to stick to the moulds; consists in ladling molten wax upon the wicks suspended from an See also:iron See also:ring. When of the desired thickness the candles are rolled under a See also:plate on a See also:marble slab. • In drawing, used for small tapers, the wick, rolled on a See also:drum, is passed through the molten wax or paraffin, See also:drawn through a circular hole and slowly See also:wound on a second drum; it is then passed again through the molten material and through a somewhat larger hole, and reeled back on the first drum, this process being repeated with larger and larger holes until the coating is of the required thickness. In moulding, a number of slightly conical moulds are fixed by the larger extremity to a See also:kind of trough, with their tapered ends projecting downwards and with wicks arranged down their centres. The molten material is poured into the trough and fills the moulds, from which the candles are withdrawn when solidified. See also:Modern candle-moulding See also:machines are continuous in their operation; long lengths of wick are coiled on bobbins, one for each See also:mould, and the See also:act of removing one set of candles from their moulds draws in a fresh set of wicks. " Self-fitting ends," which were invented by J. L. See also:Field in 1864, and being shaped like a truncated See also:cone enable the candles to be fixed in candlesticks of any See also:diameter, are formed by means of an See also:attachment to the tops of the moulds; spirally twisted candles are, as it were, unscrewed from their moulds. It is necessary to be able to regulate the temperature of the moulds accurately, else the candles will not come out freely and will not be of See also:good See also:appearance.

For stearine candles the moulds are immersed in tepid water and the cooling must be slow, else the material will crystallize, though if it be too slow cracking will occur. For paraffin, on the other See also:

hand, the moulds must be rather hotter than the molten material (about 2000 F.), and must be quickly cooled to prevent the candles from sticking. A candle-See also:power, as a unit of light in See also:photometry, was defined by the (See also:London) See also:Metropolis See also:Gas Act of 186o as the light given by a sperm candle, of which six weighed 1 lb and each burned 120 grains an See also:hour. See W. Lant See also:Carpenter, Soaps and Candles (London, 1895) ; C. E. Groves and W. Thorp, Chemical Technology, vol. ii. " See also:Lighting " (London, 1895) ; L. L. Lamborn, Soaps, Candles and Glycerine (New See also:York, 1906) ; J. Lewkowitsch, See also:Oils, Fats, and Waxes (London, 1909).

End of Article: CANDLE (Lat. candela, from candere, to glow)

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