In the year 1830, a solid substance, resembling wax in most of its properties, was obtained by M. Manicler, a French chemist (lately deceased), from palm oil, an English patent for which was taken out in conjunction with Mr. James Collier. The specification states that the process consists in placing the palm oil, or butter of palm, in a metallic vessel or boiler, made of tinned iron, and provided with a close cover and safety valve, upon the principle of Papin's Digester ; water, in the proportion of about one-sixth part to the sub stance being added. The vessel being well closed, it is submitted to the action of fire, so as to raise the steam to a pressure of two or three atmospheres, which operation is to be continued for two hours. After the material has been thus prepared, it is to be put into wrappers of linen or woven horse hair, or both may be used, and submitted to powerful pressure: by this means the Wain, or fluid oil, is separated, and the stearin remains in the wrappers in a solid state. Both these products are of a yellowish brown colour, and require a process of bleaching to deprive them of it. We have seen candles made from the stearin of palm oil, which were very little inferior to wax in illuminating power; they were cast in moulds, from which they readily separated by con traction when cold, in this respect possessing an advantage over wax. The odour emitted by the substance is like palm soap, and is generally considered rather agreeable than otherwise. It may, perhaps, be necessary to explain to the general reader that the palm oil of commerce, and that to which the last mentioned patent relates, is the produce of a tree growing abundantly in Africa and South America, where, as well as in other parts of the world, it is obtained from the outer shell or pulpy rind of the palm nut, while the kernel of the nut contained within the inner indurated shell is thrown away as useless in the preparation of oil or other oleaginous articles of commerce. These kernels, however, have been recently found to abound in oleaginous matter of superior quality, eminently calculated for the production of candles, besides generally for those purposes for which fluid and concrete oils are used. For the introduction and application of this valuable (refuse) matter, the public is indebted to Mr. John Demeur, who has recently taken out a patent for this interesting discovery. The process described by the patentee in his specification is as follows: "I first subject the kernels to a slight heating in an oven, or other convenient apparatus, carrying the process only so far as to render the kernels comparatively crisp and brittle when cold, which facilitates the subsequent operation of grinding them to a paste in a mill. This paste I dilute with one fourth of its weight of boiling water, and then put it into bags (of the usual kind employed in oil mills), wherein I subject it to mechanical pressure by the ordinary mechanism employed for similar purposes, preferring, however, to place the said bags containing the paste between heated metallic plates. By the joint action of heat and pressure so applied, the oleaginous matter is copiously exuded through the interstices of the bags, and is collected in suitable receivers to undergo a purification. This purification I usually effect by remelting the last mentioned product, and filtering it whilst in a fluid state ; and if it be desired to purify or refine it still farther, or to remove the slight tine of colour it may yet possess, I again melt it in a metallic vessel coated with tin, and mix therewith, by agitation or stirring, some very dilute sulphuric acid. By this process the Impurities are precipitated, or subside, by rest, to the bottom of the vessel, and the oleaginous matter floats above the water, whence it is removed, and subsequently consolidated, by evaporating the aqueous particles that were commixed with it in the previous operation. The product resulting from the last described process is a white and partially concrete matter, as it consists of the two distinct substances, termed elain and stearin, the former of which is fluid, and the latter solid, at our ordinary atmospheric temperature. To separate these, they are subjected again in bags to mechanical pressure, without the aid of artificial heat, if the weather be warm ; but if the air be under 650, the application of a slight degree of heat will assist the operation, and cause a fine fluid oil to be expressed, leaving the stearin in the bags of a similar consistence to wax or spermaceti, and from which candles, scarcely inferior to those fabri cated of the last mentioned substances, and very superior to those of tallow, are made. Having noticed the several important materials that have been introduced into the modern manufacture of candles, we shall proceed to describe some very recent and ingenious improvements in their construction and com position, which have been the subject of patents.
Dr. Bulkeley, of Richmond, in Surrey, took out a patent, dated January 26, 1830, for a plan of making tallow candles with an exterior casing of wax, and also for effecting a saving in the material used for wicks, as well as to obviate the necessity of snuffing. He uses a metallic mould, of the description generally. employed in the manufacture of mould candles, and fills it with melted wax. Now, as the portion of the wax which is in contact with the interior surface of the mould will become, by the conducting powers of the metal, first cooled or set, as it is termed, the wax remaining fluid in the centre of the mould is poured otg leaving within the mould a hollow cylinder of wax, which is afterwards filled with tallow, or any other material which melts at a lower temperature than wax. With respect to the wick, the patentee introduces a small thread up the centre of the candle, for the purpose of constituting a guide for a short cotton wick, which is plaited with a piece of straw within it, to receive the thread. This short wick rests on the surface of the tallow, which it raises by its capillary attraction for the supply of the combustion ; and as it descends upon the thread as the tallow is melted, the top of it is never removed so far from the tallow as to carbonize and require snuffing, which is the case with wicks of the ordinary construction. The ordinary mode of manufacturing wex candles, described in the early part of this article, has, we understand, been resorted to, on account of the presumed difficulty of removing them from the moulds, to which they firmly adhere, if cast therein. To obviate this difficulty, Dr. Bulkeley places a block of box-wood, having a cavity in it to receive the lower ends of the candle, in contact with the annular edge of the mould; then striking the block a few smart blows with a mallet, he detaches the candles from the moulds.
A patent wag also granted on the 4th February, 1830, to Mr. Charles T. Miller, of Piccadilly, Westminster, for certain improvements in making candles. These consist in the use of a small glass ring, which is placed over the wick, and descends as the candle bums. The object in view is to prevent the candle from wasting or guttering, which it effects by the glass ring conducting a greater quantity of heat to the centre of the candle than that which reaches the exterior; so that candles provided with this ring burn hollower in the centre than others, and the exterior tallow, or composition of which the candles are made, stands higher, and descends to the wick as soon as it is melted. The method of manu facturing the candles with the glass rings, as described by the patentee, consists in putting the ring over the wick after it has been placed in the centre of the mould, which, being inverted, as it is while being filled with the oleaginous matter, the ring descends until it reaches that part of the conical extremity of the mould which is equal in diameter to the exterior of the ring, when it rests, and becomes fixed in the candle. From an experiment which we have witnessed with spermaceti candles, made by Mr. Miller according to the plan described, they appear to answer the purpose intended.
Mr. John Murray, in a letter to the editor of Bretoster's Journal, states that tallow candles may be materially improved by previously steeping the cotton wicks in lime water, in which there has been dissolved a considerable quantity of the nitrate of potass. The chlorate of potass is preferable to the nitrate, but the great expense of the former salt precludes its employment on the large scale. The wicks should be well dried before the tallow is put to them. By this Mr. Murray states that the candles afford a purer flame and a more brilliant light; the combustion of the wick is so complete as to render the snuffing of them nearly superfluous ; and that they do not run or gutter.
With similar objects in view, Mr. William Palmer, of Wilson-street, Finsbury square, London, obtained a patent, dated 10th August, 1830. He applies to about a tenth portion of the strands composing the wick, a quantity of bismuth in a finely divided state, or else the nitrate, or any other similar preparation of bismuth. The portion of wick thus prepared is to be surrounded with more strands, till it becomes half the thickness required for the wick. It is then to be cut into pieces, corresponding in length with twice that of the candle for which it is intended. The wick is next twisted spirally round a thick wire in contrary directions, a notch being made in the lower end of the wire to receive the middle of the wick ; and the upper end is bent into a rectangular loop, to retain the two ends of the wire together, and to facilitate its removal when the making of the candle is completed, which is to be effected by either moulding or dipping in the usual manner. The combustion of the wicks of candles manufactured in this way, with a portion of bismuth in combination with the wick made of the double spiral form, causes the two upper extremities of the spiral, in the act of burning, to curl over to the opposite sides of the candles, where they are accessible to an additional quantity of oxygen, and the com bustion is in consequence so intense as to leave no carbonaceous matter to impede the light, or to require removal by snuffers. We shall close our article on this subject by the translation of a French Brevet d'Invention, granted to M. Lorraine, of Paris, for the manufacture of perfumed imitative wax candles, which we think is calculated to afford some useful practical hints to the British tallow chandler. "Candles made of tallow only." observes M. Lorraine, "are unctuous, opaque, greasy, little sonorous, especially in summer, liable to run or gutter, and readily acquiring a rancid smell. These inconveniences are avoided by putting fat, which has been melted and run into cakes, to ferment in a stove where the heat is moderate ' • this fat distils, and throws of an oily liquor, which is removed with a piece of linen or a sponge. To free the grease from the fleshy and fibrous parts by which it is accompanied, it is first chopped, and after being washed in several waters, it is boiled with a given quantity of Roman alum. The alum soon separates and destroys the heterogeneous parts, and we obtain a pure clear fat, which will last a very long time. The fat chopped and melted, is run into buckets Rill of water distilled from aromatic simples, such as lavender, thyme, rosemary, &c. The fat and water are beaten together with a spatula, to effect an union. After forty-eight hours the fat is separated from the water, by means of a water bath ; the water alone is disengaged, and the aromatic and odoriferous parts remain incorporated with the fat. To complete the purification, the fat is liquefied and scummed, till no foreign substance nor water remains : Ibis will be known by the limpid state of the fat, which then yields only a pure white scum. Still greater purity is obtained by a second quantity of alum incorporated with the tallow. Before casting or running the candles, a composition is made of half wax and half spermaceti, which serves to prepare the wicks. This composition, harder and more cohesive than the tallow, makes the candles less subject to gutter, to become firmer, last longer, and require less snuffing. At the moment of removing the pure liquefied tallow from the fire to cast the candles, a certain quantity of gum Arabic, dissolved in water, and united with a small quantity of wax and alum, is incorporated with it. The whole are beaten together; and when the tallow has settled well, and cooled to a certain temperature, it is poured into the moulds. By this preparation, in pro portion as the cooling takes place, the foreign substances proceed to, and fix at the surface of the candles, forming a kind of covering pleasant to the touch, like wax candles. This covering also prevents the candles from guttering, and enables a person to handle and even rub them without greasing the fingers, and without communicating any other smell than that of the aromatics entering into the composition. The last operation for preventing the guttering of the candles when burning, and giving more solidity to them, is to prepare some glover's size very weak, and boiled with another quantity of gum and alum, and to pass a hair pencil dipped in this size, all over the candles, and the next day after they may be used. Candles prepared in this way are clear, transparent, sonorous, and last longer than others ; they feel like bougies, and have the colour of pure wax."