Wax candles are also of various kinds ; they are made of cotton or flaxen wicks, and covered with white or coloured wax, which is performed either by the ladle or by the hand. In making them by the ladle, a dozen of them are tied by the wick at equal distances round an iron ring, suspended over a large basin of copper, tinned on the inside, and full of melted wax ; a large ladleful of this wax is gently poured on the tops of the wicks one after another, and the operation continued till the candles arrive at their destined dimensions. The first three ladlesful are poured on to the tops of the wicks, the fourth at the height of three-fourths, the fifth at one half, and the sixth at one-fourth, in order to give the candles their proper form, which are then taken down and smoothed by rolling upon a walnut-tree table, with a smooth box-wood instru ment, which is continually moistened with hot water to prevent the adhesion of the wax. In making wax candles by the hand, the workmen begin to soften the wax by working it several times in hot water, contained in a deep narrow cauldron. A piece of the wax is then taken out and disposed by little and little around the wick, which is hung on a hook in the wall, by the extremity opposite to the neck, so that they begin with the large end, diminishing still as they descend towards the neck. In other respects, the method is nearly the same as in the before mentioned. There is, however, this difference,—that in the former case, water is used to moisten the instruments, while in the latter, the hands are lubricated with oil of olives, or lard, to prevent the adhesion of the wax. Wax tapers are drawn after the manner of making wire. By means of two large wooden rollers the wick is repeatedly passed through melted wax contained in a basin, pro vided on one side with an instrument full of holes, through which the cylinder of wax also traverses until it has obtained the required size.
Candles are made from spermaceti, the process being very similar to that employed in making them of tallow ; they are also made of various mixtures of tallow, spermaceti, and wax ; certain proportions of which con stitute the article termed composition candles. The meritorious investi gations of M. Chevreul, concerning the true nature of fatty substances, which were published a few years ago in the Alludes de Chinaie, appear to have opened a wide and diversified field for the operations of the manufacturer and the experimentalist. By dissolving fat in a large quantity of alcohol, and observing the manner in which its different portions were acted upon by this substance, and again separated from it, M. Chevreul found that fat is composed of an oily substance, which remains fluid at the ordinary temperature of the atmosphere, and of another fatty substance which is much less fusible. Hence it follows that fat is not to be regarded as a simple principle, but as a combi nation of the above two principles, which may be separated without alteration. To the former of these substances, which melts at Fahr., and has very much the appearance and properties of vegetable oil, M. Chevreul gave the name of elain, and to the latter, which melts at 1000, he gave the name of stearin ; this is separated from the former by crystallization in the form of small silky needles, while the elain is obtained by evaporating the spirit. M. Bracconet subsequently employed a simpler process to obtain the elain and stearin; he squeezed the tallow between folds of porous paper, which absorbed the elain, leaving the stearin between ; the paper being afterwards soaked in water, yielded up its oily impregnation. The principle of M. Brac conet's process is now extensively applied by manufacturers, who employ powerful presses to squeeze the fluid oil from the tallow. In the year 1825, M. Gay Lussac, the celebrated French chemist, also took out a patent for this country for the employment of the stearin (termed likewise margaric acid from its chemical properties) in the manufacture of candles; the patent likewise ex tending to a new mechanical construction of candles. Of the several processes that may be employed for obtaining the margaric acid for this purpose, two are particularly descriptive in the specification, namely, saponification and distilla tion The first is to be effected by incorporating any of the alkalies with the fat, as is done in the making of soap, and then decomposing the soapy fluid by an acid that has the greatest affinity to the peculiar alkali employed. It is recommended that the decomposition be effected in a large quantity of water, heated by steam, which should be kept well stirred. Being afterwards allowed to rest, the products will float on the surface in a condensed and solid form. If the tallow or fat, thus purified from the matters soluble in water, should still contain any of the salts employed in the previous process, it is to be washed by additions of fresh quantities of warm water, until they are perfectly discharged This being done, and the mass of fat having become solid by cooling, it is to be subjected to the action of a powerful press, similar to those used for expressing oil from seeds, when the fluid oleic acid (or slain) will run oft leaving the mar• garic acid in the press, from which product the candles are to be made. The distilling process is conducted by exposing the fat, in an ordinary still, to the heat of a furnace. Steam is also to be introduced into the still to facilitate the operation, and to carry over those products which are soluble in it, through the worm or condenser, into a receiver. Care must be taken in regulating the heat of the furnace, to prevent discolouring the materials in the still The fat thus prepared is to be purified by washing, and then subjected to pressure as in the previously described process. Fot the more perfect purification of the fat, both the foregoing operations of saponification and distillation may be combined, and the residue after subjected to pressure. The margaric acid may also be bleached by exposure to the air and sun the same as in the bleaching of wax ; the oleic acid, or fluid oil, tray also be whitened by similar means, and be applied generally to the same purposes as the vegetable oils. The form of W. Gay 's candles is that of hollow cylinders, through which a stream of air passes to the wick (on the principle of the argand burner in lamps) for the pur pose of producing a perfect and vivid combustion of the tallow. He directs that the wick be formed of cotton yarn twisted rather more closely than usual; this yarn is to be wound spirally mini' a metallic rod or thick wire, in the same manner as wire is sometimes coiled round the large strings of musical instruments. These rods, covered as described, are to be inserted into the moulds used for making candles • and when the candles have been cast, and the tallow become hard, the wires are to be withdrawn, leaving the wicks behind in the candles with a perforation, or air passage, equal to the size of the rods, throughout their whole length.
We have thought it proper to introduce this account of M. Gay Lussae's specification of his patent, because it affords clear and judicious instructions in cohducting similar operations. The pro.. ceases possess scarcely any originality in the mode of procedure ; i and as regards the invention of the candle itself, the French chemist is just twenty years behind two of our own countrymen, namely, Messrs. Desormeaux and Hutchings, who took out a patent for the identical contrivance in the year 1805. It is per 6p worthy of notice here, that this invention aflbrds a very remarkable proof that many individuals may, without communi cation or knowledge of each others' ideas, invent precisely the same thing. The writer of this article, about ten years ago, spon taneously thought of the same contrivance, and made a candle of the kind, which is represented in the annexed cut. The dotted lines at a mark out the central aperture for the air; and the wick, which is bedded in the middle of the thickness of the hollow cylinder of tallow, is • common argand wick. This candle although not fabricated in a workmanlike manner, gave gool indications of success under proper management. Upon mention ing the project to some friends, We learned to oursurrise that several other persons had entertained the same propositions, each person imagining himself to be the sole inventor. In like manner we were informed by the before.menfloned gentleman, Mr. Desormeaux, that he had patented the invention at the time stated; that a large manufactory was commenced for the purpose of making the article, with every probability of success ; and that the reason why the manufacture of them, was not carried forward, had no refer ence to the practicability of the scheme. Seeing that the subject has been taken up by scientific as well as practical men, we are confirmed in our opinion that important results may yet flow from prosecuting the plan, if undertaken by some intelligent person. We are not wholly indebted to the animal kingdom for a supply of the material for candles, several vegetable oleaginous substances having been recently introduced as valuable substitutes. On the 2d of Novem ber, 1829, a patent was granted to Mr. John Soames, jun. of Spitalfields, for the right of separating the constituent principles of the cocoa-nut oil of com merce, which, from its consistence at ordinary temperature, is also called " butter of cacao." Before the date of this patent, cocoa-nut oil was of very limited utility, owing to the presumed necessity of artificial heat to render the mass sufficiently fluid to be burned in lamps, and to that apparent want of solidity which is required in the manufacture of 'candles. Mr. Soames's pro cess for separating the fluid from the solid matter in cocoa-nut oil is as follows:— the oil is put into strong linen bags, 2 feet long, 8 inches wide, and 1 inch thick; these are covered with stout sack-cloths made for the purpose, and are laid flat upon the horizontal bed of a hydrostatic press, leaving a small vacant space between the bags. Pressure is then given to them, and continued until the oil ceases to flow, or is only given out by drops slowly. This oil being received into a cistern, is allowed to stand a little time to deposit its impurities, after which it is drawn off clear, and preserved for burning in lamps, &c. The solid portion being now taken out of the bags in the press, is next to be purified from the other vegetable principles with which it is usually combined, such as fibre, mucilage, &c. For this purpose it is put into a covered boiler of tinned copper, which is immersed in a water-bath to prevent the liability of an excess of heat; there is then added to it two parts, (or two per cent.) by weight, of sulphuric acid, of spec. gray. 1.8, diluted with six parts of water. Boiling then coagulates and precipitates the foreign matters, which may be separated by skimming, straining, or filtering, while warm in the fluid state, and by allowing them to settle in the cold state. The substance thus obtained is of firm con sistence, and forms a valuable material in the making of candles that are now extensively used. In the Quarterly Journal of Science, an interesting account is given of the piney tallow tree of India, which we introduce in this work, as the writer observes, that " it may be imported into this country at less than one-fourth the price of wax ; and that although it does not possess all the advantages of that substance, it is considerably superior to animal tallow." This substance, he says, "is a concrete inflammable, partaking of the nature of wax and oil, which, from its appearance, may not inaptly be termed a tallow. It is in use only in the town of Mangalore (province of Canara), and is there em ployed medicinally as an external application for bruises and rheumatic pains ; and likewise, when melted with the resin of the same tree, is used as a substi tute for tar in paying the bottoms of boats. The method of preparing this material is simply to boil the fruit in water, when the tallow is soon found to rise to the surface in a melting state, and on cooling forms a solid cake. Thus obtained, the piney tallow (piney is the native name of the tree which produces it) is generally white, sometimes yellow, greasy to the touch, with some degree of waxiness, almost tasteless, and has a rather agreeable odour, somewhat resembling common cerate. It melts at a temperature of 97i°, and conse quently remains solid in the climate of India, in which respect it differs from palm or cocoa-nut oil : wrapped up in folds of blotting paper, and submitted to strong pressure, scarcely sufficient oil, or elain, as it is termed by M. Bracconot, is expressed to imbue the inmost fold. Its tenacity and solidity are such, that when cast in a rounded form of nine pounds' weight, the force of two strong men was not sufficient to cut it asunder with a fine iron wire, and even with a saw there was considerable difficulty in effecting a division. When manufactured into candles, it comes with facility from the moulds, thus differing from wax, which does not readily admit of being cast; it gives as bright a light as tallow, and has the advantage of that material in being free from unpleasant smell, and in not emitting a disagreeable odour when extin guished. It unites, in all proportions, with wax, spermaceti, and tallow ; and forms compounds with the two former, intermediate in their melting points, according to the proportion in their ingredients, and better adapted to the purpose of making candles than the pure and more fusible substance itself." With the view of ascertaining the comparative combustibility of piney tallow, candles of the materials undermentioned were cast; one mould was used for all, and the wicks were composed of an equal number of threads. Having been accurately weighed, they were burned for one hour in an apartment in which the air was unagitated, and at a temperature of 55°.