For preparing wax tapers, the wick is wound around a drum and is then made to pass into the melted wax under a hook placed at the bot tom of the kettle. The wick, coated with wax, traverses a draw-plate which gives it the de sired diameter, and then winds around a sec ond drum. A little tallow, resin and turpen tine is often added to the wax in order to give it greater ductility.
Wax matches, also, which are generally of paraffine, are made with the draw-plate. They are afterward cut to the proper length and tipped with a paste of inflammable material. The use of wax for candles, by reason of their cost, was never very widely diffused, and of course at the present day is likely to diminish greatly. See WAX.
Hollow candles are provided with three apertures extending throughout their entire length. They offer the advantage of not gutter ing when burning. They are manufactured by means of a special machine, the molds of which contain three solid rods, which are withdrawn before the solidification of the mass.
At the beginning of the 18th century, sper maceti, a product of the cachalot, or sperm whale, came largely into use for the manufac ture of candles. The competition of other ma terials and the decline of the whale fisheries limit its use at the present day.
Cetin, a form of spermaceti, is too brittle and lamellar in texture to use alone in candle making. These defects are corrected by the addition of about 3 per cent of wax.
Paraffin candles came into general use about 1850. When crude petroleum is distilled the products obtained consist of light oils em ployed for illuminating purposes, and heavy oils used as lubricants. These latter, upon cool ing, yield a solid substance of waxy consistence and deep color, called paraffine. This material, when purified, gives a white, odorless com bustible substance, which is made into candles which give a brilliant but slightly smoky flame. Objections to their use are that at the moment of extinction they emit a disagreeable odor, and that they are too fusible and apt to become dis torted in a warm atmosphere. For these rea sons paraffine is generally mixed with stearic acid. The use of paraffine candles is most com mon in Great Britain. See PARAFFINE.
Ozokerit, or ceresine, which is also used in the manufacture of candles, resembles paraffine in appearance. It is obtained by purifying a sort of natural mineral wax, the principal de posit of which is found in Galicia. It is not much used except in Germany and Austria. Since ceresine candles melt at a higher tem perature than paraffine, they undergo no de formation when used.
Palm-oil is obtained from the west coast of Africa, especially the neighborhood of Lagos. The palm which yields it is the Elias guineensss, which produces a golden-yellow fruit of the size and shape of a pigeon's egg. By detaching its pulp from the kernel, bruising it into a paste, and then agitating it in boiling water, the oil is separated, and, rising to the surface, con cretes as the water cools. About two-thirds of it in weight consists of a peculiar, white, solid fat, called palmitine; the remainder is chiefly olefin.
The manufacture of candle-wicks is fully as important as the treatment of the combustible fats, and candle-makers have studied the princi ples of combustion with a view to discovering methods of producing the clearest light with the minimum of smoke, odor and trouble in snuffing.
A flame is the result of the combustion of a gas. In a burning candle the fatty or other substances are melted and carried by the wick into the interior of the flame, where they are continuously converted into gas. We may com pare the combustion of a candle to a micro scopic gasworks, and, just as the gas-burner gives more or less light according as the pres sure is varied, or the tip is more or less foul, or the proportion of air that reaches the gas is greater or less, just so a candle will give a different light according to the draft of air, the size and nature of the wick. Too large a wick would absorb the melted material too rapidly, the flame would be unduly increased, and the feeding of it would be effected under unfavorable conditions. Too small a wick would produce the opposite effect; around the periphery of the candle there would form a rim, which, no longer receiving a sufficient quantity of heat, would remain in a solid state; the cavity that serves as a reservoir .for the liquefied material would become too full; and the candle would gutter. So the section of the candle, the size of the wick and the draft of air in the flame must be apportioned in such a way that there shall always be an equilibrium between the quantity of material melted and that decomposed by the flame. The purity of the air, too, must be taken into account, for, just as a man needs pure air in order to live in health, so a candle has need of the same in order to burn well. During an evening party it may be observed that the brilliancy of the candles diminishes in measure as the air be comes impoverished in oxygen and enriched with carbonic acid.
The wick must be placed in the centre of the candle, or else it will remain too long, produce smoke, and darken the flame. If the end re mains exactly in the centre the air will not reach it, and the wick will carbonize and form a ((thief') or ((waster," which, falling into the cavity at the top of the candle, will make the latter gutter, and end by obstructing the wick. It then becomes necessary to snuff it. In order to do away with this inconvenience, Gay-Lussac and Chevreul, in 1825, recommended the use of flat or cylindrical wicks of an uneven texture, having the property of curving over. In the same year Cambaceres proposed the use of hol low plaited wicks, which, in measure as the candle burned, had the property of curving toward the white part of the flame. But ashes nevertheless formed, and, obstructing the wick, affected the light. In the month of June 1826 De Milly finally succeeded in solving the prob lem by impregnating the wick with boric acid. This latter, uniting with the ashes of the wick, gives rise to a fusible body, which is rejected in the form of a drop or bead toward the ex tremity of the wick. In Austria, wicks are impregnated with phosphate of ammonia, which gives analogous results. Bailey has proposed a solution of sal-ammoniac of 2° or 3° Baum& Consult Calderwood, of Candles> (London 1891) ; Lamborn Soaps, Candles and Glycerine' (tb. 1906) ; witsch, (Chemical Technology and Analyses of Oils, Fats and Waxes' (Vol. II, London and New York 1909).