11. Wax candles. Next to tallow, the substance most employed in the manufacture of candles is wax. Wax candles are made either by the hand or with a ladle. In the former case, the wax being kept soft in lot water, is applied bit by bit to the wick, which is hung from a hook in the wall; in the latter, the wicks are hung round an iron circle, placed immediately over a large copper tin ned bason•ull of melted wax, which is poured upon their tops, one after another, by means of a large ladle. When the candles have, by either process, acquired the proper size, they arc taken from the hooks and rolled upon a table, usually of walnut-t•ee, with a long square in strument of box, smooth at the bottom. As the candles ,,,.,et be rolled one by one, in order to preserve their warmth, anti Keep the wax soft, those made with the la dle are laid, previous to rolling, in a feather-hed fold ed in two, at convenient distances from one another. The same precaution is not so necessary with the candles made by the hand, as they may be rolled just as they are formed. Besides the common cylindrical form, wax candles are sometimes made of a conical figure, and arc intended chiefly to illuminate churches. and to be used in processions and funeral ceremonies. The pyramidal form is given them, by pouring the wax upon the wicks at different heights: the three first ladles are poured on at the top of the wick ; the fourth ladle at the height of three-fourths ; the fifth at one-half; and the sixth at one fourth. Candles of this shape, after being rolled and smoothed, have their big end cut off, and a conical hole made in it to receive the point in the candlestick. There is still another kind of wax candle, or taper, said to be the invention of Pierre Blassimmere of Paris, and brought by him from Venice about the middle of the 17th century. The process consists in mz.king a wick, of some yards in length, pass several times through a brass bacon of melted Nvax, and at the same time through the holes of an instrument like that used for drawing wire, by means of two rollers of wood turned by a handle.
We shall now give an account of the different im provements which have been suggested upon the manu facture of the common candles, and mention some of those substances which have been proposed as substi tutes for tallow and wax. It will be necessary, however, previously to explain the process of burning in candles, and to state the comparative advantages of the two sub stances usually employed.
The wick of the candle being always a combustible: substance, readily catches fire upon the application of a flame. The heat thus produced fuses a portion of the tallow, or wax, which immediately rises through the fibres of the wick by a kind of capillary attraction. The melted matter, as it approaches the flame, is gra dually volatilized and set on fire ; a new portion of melt ed tallow, or wax, ascends in the same manner, and is, in its turn, heated and burned : and in this way a constant combustion is maintained. A candle differs from a lamp, chiefly in the circumstance, that the tallow, or wax, is melted gradually, and in small quantities, and is retained in a cup formed by the solid part of the candle. As this cup must obviously be of very small dimensions, it is of the last consequence that the quantity of matter melted never exceed the power of the wick to absorb it, other wise the candles will gutter. The size of the wick, therefore, must always be proportioned to the fusibility of the substance employed ; the more fusible substance obviously requiring the larger wick. Of the two sub
stances commonly used, wax is the least fusible. Tal low melts at 92° of Fahrenheit, spermaceti at 133°, and bleached wax at The flame of wax is less bril liant than that of tallow, which is supposed to be owing to the wax being already combined with a portion of oxy gen. This disadvantage, however, is more than com pensated by its being less fusible ; by which means a smaller wick may be used, which not only affords the ad vantage of a clear perfect flame, but, in consequence of its flexibility, it naturally falls to one side, and, by thus coming in contact with the air, is burnt to ashes. The wick of the tallow candle being much larger, preserves its position in the centre of the flame, which is less per fect, from its internal part not being completely exposed to the action of the air. As the burning prut-eeds) the wick lengthens, and, consequently, the distance between its top and the point of the flame diminishes ; from which it follows, that the oil which issues from the extremity of the wick, having a smaller portion of flame to pass through, will be less perfectly burnt, and will pass off partly in smoke. The wick soon rises above the top of the flame ; but, owing to its size, and the quantity of oil which it contains, it is not converted into ashes, and dis sipated, as in the case of the wax candle. On the con trary, the half decomposed oil is converted into a kind of coal, or soot, which gradually accumulates upon the top of the wick, and assumes the appearance of a fungus. In order, therefore, that a tallow candle may burn with any degree of clearness, constant snuffing is requisite.
From the above statement, it appears, that the chief difficulty in improving the burning of the tallow candles, arises from the great fusibility of the tallow. Several at tempts have been made to remove, or at least to lessen, the evil, hut none of them have completely succeeded. If it were possible, by means of some chemical agent, to produce such a change upon tallow, as to raise its melting point SC% era' degrees, and there is reason to believe, that some such change is produced in wax by the absorption of oxygen ; this, certainly, would be the most direct me thod of removing the evil. Several chemists, and, among others, Mr Nicholson, have engaged in experiments with this view ; but we arc not aware that their success has been in any degree equal to the importance of the object sought after. As a substitute for this desideratum, it has been proposed to strengthen the cup by covering the tal low with a thin coating of wax. A candle of this kind, called lobchark, is known at Canton in China. Mr Nichol son informs us, that he attempted to imitate this Chinese candle, by pouring a quantity of wax into a mould, and immediately pouring it out again before running in the tallow. In this way he covered the tallow with a thin film of wax ; but owing, perhaps, to the wax naturally contract ing more than the tallow in cooling, or to the sudden cooling of the wax before the tallow was poured in, he found, upon drawing the candle, that it was cracked longi tudinally on its surface. At any rate, it is not at all like ly, when we consider the additional labour and expence connected with the manufacture of this species of candle, that it will ever become an article of general use.