CANDLE, a solid cylindrical rod composed of beeswax, tallow, paraffine or some other fatty substance, with a wick running longitudi nally through its centre, designed for slow com bustion with illumination. The wick is gen erally composed of a few threads of cotton yarn lightly twisted or plaited; but formerly, in home-made candles, dried rushes (Juncus e)fusus) were employed for this purpose. The process of making rushlights is described at length by the Rev. Gilbert White in his well known 'History of Selborne.' Candles are mentioned in several places in the Bible, but no direct evidence is given as to their form or of what they were made. There seems to be a distinction, however, between can dles and lariips,— the latter specifically calling for oil, while the candle is spoken of as being lighted and placed on a candlestick.
Considerable modern improvements have been made in the manufacture of candles. One of the most important of these consists in not employing the whole of the fatty or oily sub stances, but in decomposing them, and then using only the stearin or stearic acid of the former, and the palmitine of the latter class of substances. The animal fats are combinations of glycerine and fatty acids, principally stearic and palmitic, both solids, and oleic acid, which is liquid. If the latter be in excess, the fat will be a liquid and constitute an oil; if, on the contrary, the solid acids predominate, we shall have a more or less concrete fat, such as the tallow of the ruminants and lard of the hog. Stearic acid now constitutes the principal raw material for the manufacture of candles. The chief chemical agents employed to obtain the stearin are caustic lime, which, setting free the glycerine, produces stearate, margarate and oleate of lime, in the form of a solid soap; and dilute sulphuric acid by which this solid soap, after being reduced to powder, is effectually freed of its lime. By means of a subsequent bleaching process cakes of a perfectly white color, free from impurities, and fit for the manufacture of candles, are obtained.
Candles are commonly made by dipping, molding or rolling. The former is the older method, and consists in arranging in a frame a number of wicks of the proper length and thickness, and dipping them a number of times successively in a tank of melted tallow or other fatty composition, with intervals for the incipi ent forms to cool and harden. These dippings
are repeated until the candles have assumed the requisite thickness and weight.
Molded candles, as their name implies, are formed in molds. These are generally made of pewter, or an alloy of 20 parts of tin and 10 of lead, though glass has also been introduced. They are hollow cylinders of the length of the candle, and open at both ends, but provided at the upper end with a conical cap, in which there is a hole for the wick. A number of these molds are inserted in a wooden frame or trough with their heads downward; the wick is then drawn in through the top hole by means of a wire, and kept stretched and in the centre by a peculiar arrangement. The molds thus prepared are filled by running melted tallow of the proper temperature from a boiler into the trough. The candles remain in the molds for about 24 hours, but, as they improve by keeping, generally re main in the storehouse for a few months before they are exposed for sale.
The rolling of candles is confined principally to those made of wax. Although the bleaching of wax was described by Pliny, the use of this material for the manufacture of candles dates back only to the beginning of the 4th century. From its tenacity, and the contraction which it undergoes in cooling, wax cannot be formed into candles by melting it and then running it into molds. Instead, wicks, properly cut and twisted, are suspended by a ring over a basin of liquid wax, which is poured on the tops of the wicks, and, gradually adhering, covers them. Or the wicks may be immersed, as in the case of tallow "dips." When a sufficient thickness is obtained, the candles, while hot, are placed on a smooth table kept constantly wet, and rolled upon it by means of a flat piece of wood. In this way they assume a perfectly cylindrical form. Machines have been constructed, how ever, for the manufacture of such products. The large wax candles used in Roman Catholic churches are merely plates of wax bent round a wick and then rolled.