Part 92

Previous to the paraffin being made into candles, it is necessary that it should be purified and bleached. Many processes for effecting these ends have been devised. In the works of Price's Candle Company the method known as "Hodge's" is had recourse to. This consists in first freeing the crude paraffin from the coarser impurities, melting it, casting it into cakes, and allowing it to cool sufficiently slowly, so as to form well-defined crystals. The cakes are then placed upon a bed of some porous and absorbent material, and subjected to a temperature not sufficient to melt the paraffin, but only the liquid hydrocarbons and other more easily fused bodies, the latter running off from between the crystals of the paraffin, and being absorbed by the porous substance upon which the paraffin rests. This process is repeated until the removal of the liquid hydrocarbons from the solid paraffin has been satisfactorily accomplished. If it be requisite to subject the paraffin to further purification, the following method is frequently adopted. The paraffin, previously melted by steam, is placed in a tank, with from 5 to 10 per cent. of strong sulphuric acid, and the mixture agitated for some hours by means of air (the time depending on the quality of the paraffin), the sulphurous acid fumes resulting from the reaction being carried off by a suitable contrivance. After the agitation is completed, the paraffin, after being allowed to stand for some time, is decanted into a suitable vessel containing animal charcoal, with which it is digested for some hours. Upon the subsidence of the charcoal the paraffin is drawn off if at all turbid, and is passed through a funnel heated by means of a steam jacket.

Another method, the invention of Messrs Fordred, Lambe, & Sterry, for the decolorisation of the paraffin employed in candle manufacture, consists in digesting the paraffin at a temperature of 230° F. with about 12% of powdered fuller's earth. Of late this process has supplanted the charcoal one; and it may be employed, no matter by what means the previous purification of the paraffin has been carried out. The paraffin and fuller's earth are to be well agitated together, and when the latter has fallen down the clear paraffin is decanted from it. The inventors affirm that their process answers quite as well if marl clay, or any other similarly constituted and equally abundant natural substance be substituted for fuller's earth; and that no matter which of these bodies is employed, they may be re-used, and any adhering paraffin be removed by washing with agitation, or by other suitable contrivances.

Messrs Smith & Field's patent for the removal of the colouring matters of the paraffin consists in the employment of silicite of magnesium. The patentees state that the successful issue of the operation depends not only upon the careful preparation of the salt used, but upon its being dried at a temperature of as exactly as possible 212° F. The careful preparation before insisted on of the magnesium salt, which is procured by the double decomposition of magnesium, sulphate, and sodium silicate, includes its thorough washing from adhering sodium sulphate previous to its desiccation. If this precaution be neglected, the porosity of the silicate will be impaired, and its bleaching effect more or less interfered with; and further, the patentees state that if the washed silicate be heated to redness, its decolourising power will also be lost.

It appears that the paraffin employed in making the candles consists of a mixture of paraffins having different melting points. The following are the melting points of some of the chief varieties of paraffin:--

Paraffin from Boghead coal at 45° to 52° C. " " Brown coal " 56° C. " " Peat " 46·7° C. " " Rangoon oil or tar 61° C. " " Ozokerit 65·5° C.

Paraffin candles contain from 5{?} to 15 per cent. of stearin, this addition being made for the purpose of diluting the paraffin as well as for raising the melting point of the paraffin where this is low. The stearin, moreover, serves to preserve the rigidity of the candle in the candlestick, and to prevent its bending out of the upright position. Paraffin candles are always moulded, but previous to this being done the moulds must be heated to a temperature above the melting point of the paraffin; this may vary from 60°, 70°, and 87° C., according to the paraffin employed. The moulds having been filled with the melted paraffin are, after one or two moments only, plunged into cold water, when the candle immediately becomes solid. Unless this were done the candle would be spoilt, owing to the crystallisation of the paraffin. A thin wick is required for paraffin candles.

=Candles, Spermace'ti.= From spermaceti (which _see_). These are very delicate in appearance, but rather expensive. They burn well, but as the melting point of spermaceti is low, 120° Fahr., they will not bear carrying about in the hand without guttering. They are generally adulterated with stearic acid or hard white tallow.

In candle-making "spermaceti is usually mixed with 3 per cent. of wax or paraffin to destroy its highly crystalline structure; it is moulded in the usual way with plaited wicks that require no snuffing. Occasionally the spermaceti candles are cast without any admixture of wax, the moulds being raised to a higher temperature just as with stearic acid. Some manufacturers, in order to make the spermaceti appear like wax, use gamboge to give the desired tint; such candles are known as transparent wax."[236] Spermaceti candles are largely consumed in India.

[Footnote 236: 'Chemistry, Theoretical, Practical, and Analytical.']

=Candles, Stear'ic.= Under this head we may place the various sorts of candles moulded from the hard fatty acids of both animal and vegetable origin. The principal sources whence British manufacturers derive their acids are tallow, palm oil, and cocoa-nut oil. The processes employed for separating them are generally described under Stearic Acid. Candles formed of the fatty acids can now be prepared so as to imitate and almost rival those of wax and spermaceti; and they are quite as cheap as the nearly obsolete mould candles formed of common tallow. They are extremely hard; they do not grease the hands, and they burn away brightly and steadily, without giving off any offensive odour. Uncoloured, they are snowy white, but a yellow tint is frequently given them by gamboge.

=Candles, Tal'low.= From ordinary tallow or from tallow which has been freed from much of its oleic acid by pressure. These have so unpleasant an odour and are so apt to gutter, that they will probably ultimately disappear from use. They are, however, sold at so low a price, that among the lower classes they must long retain their hold. For dip candles the wicks are immersed in melted tallow, and after rubbing with the hands are placed straight and allowed to harden, after which they are arranged upon the "broaches" ready for dipping. For mould candles the last operation is omitted. Great care is taken to select a cotton that yields the least possible quantity of ash after burning.

In the process of "dipping," the "dipping cistern" being filled with tallow of a proper temperature from the boiler, one of the broaches covered with wicks is placed upon the end of the "dipping beam," and pressed down gently into the melted fat; it is then withdrawn, the bottoms of the candles just touched against a board placed on one side of the cistern for the purpose, and the frame removed to the rack. This operation is repeated until the candles acquire a sufficient size, when they are finally cooled, sorted, weighed, and strung in pounds for sale.

The mould candles once in common use were made of the finer kinds of tallow only; a mixture of 3 parts of sheep, with 1 part of ox suet, being preferred. See WAX.

=Candles, Wax.= These are most frequently made by pouring melted white wax on to the wicks, which are hung upon frames and covered with metal tags at the ends to protect the cotton from the wax in those parts. The frames are made to turn round, and melted white wax is poured first down one wick, and then the next, and so on. When the wicks have been subjected to this operation once and have become sufficiently cooled, they have a second, and then a third coat given them, until they are of the required thickness. The candles are next rolled into proper shape on a marble slab or wooden board. The conical top is moulded by properly-shaped tubes, and the bottoms are cut off and trimmed. Wax candles are now seldom moulded, but if so the same processes are followed as for stearic and paraffin candles. The large altar candles, which frequently weigh from thirty to forty pounds, are made by hand.

=Wax Tapers.= These, which are of various degrees of thickness, are not made of pure wax, but of wax (usually vegetable wax) and tallow, the latter being added to give them flexibility. When they are required to be coloured, resin and turpentine are added to the tallow. For further particulars, consult Wagner's 'Chemical Technology,' "CANDLE-MAKING."

=CANDLE NUTS.= The kernels of the _alearites triloba_, the candleberry tree, a plant growing in most tropical countries. The nuts when dried, and stuck upon a reed, are used by the natives of the Polynesian Islands as a substitute for candles. They contain a large amount of pure palatable oil, which is sometimes used by artists as a drying oil. After the expression of this oil the cake has been used as a food for cattle; also as a manure.

The following is the composition of the nuts:--

_Shells._

Water 3·71 Organic matter 89·90 Mineral matter 6·39

_Kernels._

Water 5·27 Fat 62·97 Cellulose 28·99 Mineral matter 2·79

_Ash of Kernel._

Lime 18·69 Magnesia 6·01 Potash 11·33 Phosphoric acid 29·30

=CAN'DLESTICKS.= Metallic, earthenware, and porcelain candlesticks, snuffers, and snuffer-stands, are recommended to be cleaned by pouring boiling hot water on them (previously placed in an earthen pan), and, after wiping them quite dry with a cloth, to clean them with a piece of wash leather; those made of silver, or of plated copper, may be finally polished with a little plate powder; those of white metal, with a little whiting or fine chalk, and those of brass, with a little rotten-stone or one of the polishing pastes. For articles of this kind, made of bronze and papier maché, the water should be used only hot enough to melt the tallow, and they should be only gently dabbed or rubbed off with a very soft cloth or leather. The common practice of placing candlesticks before the fire to melt off the grease is injudicious, as the solder or japan about them is almost certain to be injured. Hence the common annoyance of damaged or "crippled" candlesticks in houses where there are careless servants.

=CAN'DYING.= When the object is simply to form a confection or sweetmeat, imbued with the aroma, flavour, or medicinal property of any substance, candies are generally prepared by simply boiling lump sugar with a sufficient quantity of the infusion, decoction, tincture, expressed juice, or sometimes even the powder of the particular article, until a portion taken out and cooled becomes quite solid, when it is either poured out on a marble slab, or into tin, marble, or paper moulds, dusted with powdered lump sugar.

When the object is to preserve the form and character of the vegetable in the candy, the substance is boiled in water until soft, and then suspended in concentrated syrup (in the cold), until they become transparent; after which they are either dried in a current of warm air, or in a stove, at a heat not exceeding 120° Fahr. The syrup must be kept fully saturated with sugar by reboiling it once or twice during the process.

Another method occasionally employed by confectioners for almonds and the like is to put the substances into a syrup boiled until it forms a small thread between the opening fingers, and to stir the whole until it is nearly set. See SUGAR BOILING.

The following are the principal candied articles kept at the shops:--

=Candied Al'monds.= From blanched almonds, roasted and halved.

=Candied Angel'ica.= _Prep._ 1. From the root. Boil the fresh roots (after slicing them and removing the pith) in water, to deprive them of part of their bitterness and aroma; then drain them and put them into syrup boiled to a full candy height, and boiling hot; let them remain until nearly cold, when they may be taken out and carefully dried.

2. From the stems. From the tender stems, stalks, and midribs of the leaves, as last. Used as a sweetmeat and dessert. It is said to be cordial, stomachic, tonic, and aphrodisiac.

=Candied A'pricots.= From the fruit, scarcely ripe, either whole or cut into quarters, immersed in the syrup (hot), without any further preparation.

=Candied Cit'rons.= From the peels.

=Candied Erin'go.= From the roots, slit and washed.

=Candied Gin'ger.= From the roots of green ginger.

=Candied Hore'hound.= From a strong decoction or infusion of the root, and lump sugar, 1 pint to 8 or 10 lbs. may be used. Boil the mixture to a candy height, and pour it whilst warm into moulds or small paper cases well dusted with finely powdered lump sugar; or pour it on a dusted slab and cut it into squares.

=Candied Lem'on Peel.= As Candied Citron.

=Candied Or'ange Flow'ers.= From the flowers deprived of their cups, stamina, and pistils (2 oz. to each lb. of sugar), as Candied Almonds, but poured out on a slab.

=Candied Or'ange Peel.= From the peel of the Seville orange, or common orange, as Candied Citron.

=Candied Su'gar.= See SUGAR BOILING. The following are articles of a more special character.

=Candy, Car'away.= 1. From caraway seeds (in fine powder), 1/2 oz.; sugar, 1 lb.

2. Oil of Caraway, 1 dr.; sugar, 1 lb.

=Candy, Diges'tive.= _Syn._ LIVE-LONG CANDY. _Prep._ 1. Rhubarb and bicarbonate of soda, of each 1 dr.; ginger, 1/2 dr.; cinnamon, 20 gr. (all in fine powder); heavy magnesia, 1 oz.; powdered sugar, 2 oz.; mucilage of tragacanth, q. s. to form a lozenge mass; to be divided into small squares of 18 or 20 gr. each.

2. As the last, but adding finely powdered caraways, 1 dr.; oil of caraway, 15 drops; and sugar, 1 oz. Both are used as heartburn and digestive lozenges.

=Candy, Gin'ger.= _Prep._ 1. From ginger (in coarse powder), 3 oz.; boiling water, 1-1/4 pint; macerate in a warm place for 2 hours, strain, add lump and moist sugar, of each 5 lbs., and boil to a candy.

2. Ginger (in very fine powder), 1 oz.; powdered sugar, 2 lbs.; syrup, q. s. to make a paste. Stomachic and carminative.

For various sweetmeats which might come under the head of CANDY, see CONFECTIONS, DROPS.

=CANKER.= This disease consists in a depraved condition of that part of the sensitive foot of the horse which secretes the horny frog and sole. It mostly occurs in coarsely-bred animals, and is the result of filth, damp, and bad ventilation. The treatment consists in first removing all loose horn, and allowing all pent-up matter to escape; the exuberant granulations must be carefully cut away, and the parts then washed with a tepid lotion of sulphate or chloride of zinc; after drying the surface dust it with oxide of zinc; apply tow dipped in a mixture of tar and lime, and "keep it in firm contact with the parts by means of a leather sole or strips of hoop iron underneath a shoe lightly tacked on. Dress in this manner daily, keeping up the dry pressure for a week." (Finlay Dun.)

=CAN'NON METAL.= See GUN METAL.

=CANTHAR'IDES.= _Syn._ SPANISH FLIES, BLISTERING F., LYT'TÆ; CANTHAR'IS, B. P. The _Cantharis vesicatoria_ of Latreille, commonly known as the Spanish fly, is an insect of the order Coleoptera; it abounds in the south of France, Spain, and Italy; and has spread into Germany and the south of Russia. When alive it exudes a strong fetid and penetrating odour.

_Pur., &c._ These insects should be preserved in well-closed bottles or tin canisters. The addition of a few drops of oil of cloves, or of strong acetic acid, or even of a few cloves in substance, will preserve them unchanged for a length of time in closed vessels. The best proof of their goodness is the smell. The powder is constantly adulterated. The plan of the wholesale druggists is to sort out the most worthless flies for powdering, and to compensate for their deficiency of vesicating power by adding 1 lb. of euphorbium to every 12 or 13 lbs. of flies. When a superior article is required, liquorice powder is added (4 or 5 lbs. to every 14 lbs.), along with about 1 lb. of euphorbium, and sufficient blue black or charcoal to turn the yellow of the liquorice to a greenish colour. The best mode of detecting this adulteration is by the microscope. It should be borne in mind that only those flies which have attained their full growth possess blistering properties. The immature or undersized insects are destitute of epigastric power.

_Ant._ An emetic of sulphate of zinc, followed by the stomach-pump, if necessary. The vomiting may be promoted by copiously drinking warm bland diluents, such as broth, linseed tea, milk, &c. Friction on the spine, with volatile liniment and laudanum, and the subsequent administration of draughts containing musk, opium, and camphorated emulsion, have been strongly recommended.

_Tests._ By the microscope very minute particles may be discovered in the stomach and intestines, on a post-mortem examination. Orfila thus found particles of cantharides in a body that had been interred nine months.

_Uses, &c._ Spanish flies are used externally to raise blisters, and internally as a stimulant and diuretic, generally in the form of tincture. In excess they produce strangury, bloody urine, satyriasis, delirium, convulsions, and death. See TINCTURES, VESICANTS, &c.

=CANTHARI'DIN.= C_{5}H_{12}O_{2}. Isomeric with picrotoxin. This substance is found in, and is the vesicating principle of, the Spanish fly, Chinese blistering fly, and other coleopterous insects. _Prep._ Pulverised cantharides are allowed to remain in contact for 24 hours with twice their weight of chloroform, in a displacement apparatus. The chloroform is then drained off, and finally displaced by alcohol, and the solution is left to evaporate. The cantharidin crystallises out, saturated with green oil. In order to purify the cantharidin it is laid on bibulous paper, which absorbs the greater part of the oil, and then crystallised out of a mixture of alcohol and chloroform. (Procter.)

_Prop._ Prismatic crystals, melts at 200° C., volatilises in white fumes, which strongly irritate the eyes, nose, and throat, and condenses in rectangular prisms. Cantharidin is insoluble in water, but soluble in alcohol, ether, chloroform, acetic acid, and in the fixed and volatile oils. Its solution in any of the liquids above mentioned possesses vesicating properties, which, however, is not exhibited by solid cantharidin.

=CAOUT'CHOUC.= _Syn._ INDIA RUBBER, ELASTIC GUM. India rubber is the concrete juice of the _Ficus elastica_, _Siphonia elastica_, the _Urceola elastica_, and many other tropical plants. The fresh milky juice is spread over moulds of unbaked clay, and is then exposed to the heat and smoke of a fire, or torches, to dry it, whence it derives its dark colour. Successive coats of juice are laid on, and the operation of drying repeated until the bottles acquire sufficient thickness. When it has become thoroughly hard and dry, the clay is beaten out. In this form it is commonly imported.

_Prop., &c._ The general properties of india rubber, as well as its numerous applications, are well known. The fresh juice has a cream-like appearance and consistence, is coagulated by heat, and is miscible with water, alcohol, and wood naphtha; sp. gr. 1·012 to 1·041; it yields from 18% to 45% of solid caoutchouc, either by heat or evaporation. By excluding it from the air it may be preserved unchanged for a considerable period.

Solid caoutchouc has a sp. gr. ranging between ·919 and ·941; it melts at 248° Fahr. into a viscid mass, which does not again harden on cooling; it is unaltered by chlorine, hydrochloric acid, sulphurous acid, fluosilicic acid, ammonia, caustic alkaline lyes (even when boiling), and most similar substances; nitric acid and sulphuric acid act on it only by long contact when concentrated. Some specimens of caoutchouc are harder than gutta percha itself, and equally inelastic, whilst others never perfectly solidify, but remain in a condition resembling that of birdlime or printers' varnish.

The best solvents of caoutchouc are rectified sulphuric ether (which has been washed with water to remove alcohol and acidity), chloroform, bisulphide of carbon, a mixture of bisulphide of carbon and absolute alcohol (94 of the first to 6 or 7 of the last), and caoutchoucin. All these liquids dissolve india rubber rapidly in the cold, and leave it unaltered on evaporation. The first two are, however, too expensive to be generally employed. The others have a disagreeable odour, but are much cheaper than the rest, and possess the advantage of leaving the film of caoutchouc in a firmer and stronger condition than other solvents. Pyrogenous oil of turpentine is another cheap and good solvent. Benzol, rectified mineral or coal-tar naphtha, crude petroleum, and oil of turpentine dissolve india rubber by long digestion and trituration (with heat), otherwise they merely form with it a glutinous jelly that dries very slowly and imperfectly, leaving it much reduced in hardness and elasticity. The fats and fixed oils also readily dissolve caoutchouc (with heat), forming permanently glutinous solutions or pastes; so also do most of the volatile oils, but the solutions with the majority of them dry with difficulty.

One of the most remarkable properties of india rubber is the great amount of heat which is disengaged during its condensation by pressure or in the exercise of its elasticity. During the process of kneading the raw caoutchouc in the "masticators," the cold water thrown in to reduce the temperature soon becomes boiling hot. When no water is added, a temperature so high is often reached as to occasion the melting of the rubber. This is particularly the case during the process of "dry kneading" with quick-lime. A tube 2-1/4 inches in diameter, impactly secured, was subjected to a force of 200 tons. The result was a compression amounting to 1-10th; great heat was evolved, and the excessive elasticity of the substance caused a fly-wheel weighing five tons to recoil with alarming violence. Mr Brockedon states that he succeeded in raising the temperature of an ounce of water 2° in about fifteen minutes by collecting the heat evolved by the extension of a small thread of caoutchouc. He refers this effect to the change in specific gravity, and contends that the heat thus produced is not due to friction, because the same amount of friction is occasioned in the contraction as in the extension of the substance, and the result of this contraction is to reduce the caoutchouc thus acted upon to its original temperature.

The edges and surfaces of india rubber are readily and perfectly joined by mere contact and intense pressure. On the small scale the edges may be moistened with ether, naphtha, oil of turpentine, or some other solvent, or by long boiling in water, and immediately pressed tight together and held in contact for some time.