A plate of a calorimotor will be found at the end of this work, with a description. When this instrument is lowered into a solution, containing about a seventieth of sulphuric acid, a wire, placed between the poles, becomes white hot, and takes fire, emitting the most brilliant sparks. In the interim, an explosion usually gives notice of the extrication of hydrogen in a quantity adequate to reach the burning wire. Immediately after the explosion, the hydrogen is reproduced with less intermixture of air, and rekindles, corruscating from among the forty interstices, and passing from one side of the machine to the other, in opposite directions and at various times, so that the combinations are innumerable. The flame assumes various hues, from the solution of more or less of the metals, and a froth, apparently on fire, rolls over the sides of the recipient. When the calorimotor is withdrawn from the acid solution, the surface of this fluid for many seconds, presents a sheet of fiery foam. I ascertained that the galvanic fluid, as extricated by this apparatus, does not permeate charcoal. This demonstrates that it cannot be electricity, as of the latter, charcoal is next to metals the best conductor. See Memoirs on a New Theory of Galvanism in Silliman's Journal, Annals of Philosophy, and Philosophical Mogazine.† *CALP. An argillo-ferruginous lime stone.* * CAMELEON MINERAL. When pure potash and black oxide of manganese are fused together in a crucible, a compound is formed whose solution in water, at first green, passes spontaneously through the whole series of coloured rays to the red. From this latter tint, the solution may be made to retrograde in colour to the original green, by the addition of potash; or it may be rendered altogether colourless, by adding either sulphurous acid or chlorine to the solution, in which case there may or may not be a precipitate, according to circumstances. MM. Chevillot and Edouard have lately read some interesting memoirs on this substance, before the Academy of Sciences. They found, that when potash and the green oxide of manganese were heated in close vessels, containing azote, no cameleon is formed. The same result fol lowed with the brown oxide, and ultimate ly with the black. They therefore ascribe the phenomena to the absorption of oxygen, which is greatest when the oxide of manganese equals the potash in weight. They regard it as a manganesiate of potash, though they have hitherto failed in their attempts to separate this supposed tetroxide, or manganesic acid. When acids are poured upon the green cameleon, or an alkali upon the red, they are equally changed from one colour to the other; even boiling and agitation are sufficient to disengage the excess of potash in the green cameleon, and to change it into red. Many acids also, when used in excess, decompose the cameleon entirely, by taking the potash from it, disengaging the oxygen, and precipitating the manganese in the state of black oxide. Sugar, gums, and several other substances, capable of taking away the oxygen, also decompose the cameleon, and an exposure to the air likewise produces the same effect. Soda, barytes, and strontites, also afford peculiar cameleons. The red potash cameleon is perfectly neutral. Phosphorus brought in contact with it produces a detonation; and it sets some other combustibles on fire. Exposed alone to heat, it is resolved into oxygen, black oxide of manganese, and green cameleon, or submanganesiate of potash.* CAMPEACHY WOOD. See LOGwOOD. CAMPHOR. There are two kinds grow in the East, the one produced in the islands of Sumatra and Borneo, and the other produced in Japan and China. Camphor is extracted from the roots, wood, and leaves of two species of laurus, the roots affording by far the greatest abundance. The method consists in distilling with water in large iron pots, serving as the body of a still, with earthen heads adapted, stuffed with straw, and provided with receivers. Most of the camphor becomes condensed in the solid form among the straw, and part comes over with the water. The sublimation of camphor is performed in low flat-bottomed glass vessels placed in sand; and the camphor becomes concrete in a pure state against the upper part, whence it is afterwards separated with a knife, after breaking the glass. Lewis as. serts that no addition is requisite in the purification of camphor; but that the chief point consists in managing the fire, so that the upper part of the vessel may be hot enough to bake the sublimate together into a kind of cake. Chaptal says, the Hollanaptars ders mix an ounce of quicklime with every pound of camphor previous to the distillation. Purified camphor is a white concrete crystalline substance, not brittle, but easily crumbled, having a peculiar consistence re sembling that of spermaceti, but harder. It has a strong lively smell, and an acrid taste; is so volatile as totally to exhale when left exposed in a warm air; is light enough to swim on water; and is very inflammable, burning with a very white flame and smoke, without any residue. The roots of zedoary, thyme, rosemary, sage, the inula hellenium, the anemony, the pasque flower or pulsatilla, and other vegetables, afford camphor by distillation. It is observable, that all these plants afford a much larger quantity of camphor, when the sap has been suffered to pass to the concrete state by several months' drying. Thyme and peppermint, slowly dried, afford much camphor; and Mr. Achard has observed, that a smell of camphor is disen gaged when volatile oil of fennel is treated with acids. for two days. A gentle heat was then applied, and the digestion continued for two days longer. Six ounces of water were then added, and the whole distilled to dryness. Three grains of an essential oil, having a mixed odour of lavender and peppermint, came over with the water. The residuum being treated twice with two ounces of alcohol each time, fifty-three grains of compact coal in small fragments remained undissolved. The alcohol, being evaporated in a water bath, yielded forty-nine grains of a blackish-brown substance which was bitter, astringent, had the smell of caromel, and formed a dark brown solution with water. This solution threw down very dark brown precipitates, with sulphate of iron, acetate of lead, muriate of tin, and nitrate of lime. It precipitated gold in the metallic state. Isinglass threw down the whole of what was dissolved in a nearly black precipitate. When nitric acid is distilled repeatedly in large quantities from camphor, it converts it into a peculiar acid. See ACID (CAMPHORIC). * Camphor melts at 288°, and boils at the temperature of 400°. By passing it in vapour through peroxide of copper, Dr. Thomson converted it into carbonic acid and water. He operated upon a single grain. He infers its composition to be Mr. Kind, a German chemist, endeavour ing to incorporate muriatic acid gas with oil of turpentine, by putting this oil into the vessels in which the gas was received when extricated, found the oil change first yellow, then brown, and lastly, to be almost wholly coagulated into a crystalline mass, which comported itself in every respect like camphor. Tromsdorff and Boullay confirm this. A small quantity of camphor may be obtained from oil of turpentine by simple distillation at a very gentle heat. Other essential oils, however, afford more. By evaporation in shallow vessels, at a heat Carbon, 0.738 8 at'ms. = 6.375 73.91 not exceeding 57° F. Mr. Proust obtained Hydrogen, 0.144 10 14.49 from oil of lavender .25, of sage 21, of Oxygen, 0.118 1 marjoram .1014, of rosemary .0625. He conducted the operation on a pretty large scale. Camphor is not soluble in water in any perceptible degree, though it communicates its smell to that fluid, and may be burned as it floats on its surface. It is said, however, that a surgeon at Madrid has effected its solution in water by means of the carbonic acid. Camphor may be powdered by moistening it with alcohol, and triturating it till dry. It may be formed into an emulsion by previous grinding with near three times its weight of almonds, and afterwards gradually adding the water. Yolk of egg and mucilages are also effectual for this purpose; but sugar does not answer well. It has been observed by Romieu, that small pieces of camphor floating on water have a rotatory motion. Alcohol, ethers, and oils, dissolve camphor. The addition of water to the spirituous or acid solutions of camphor, instantly separates it. Mr. Hatchett has particularly examined the action of sulphuric acid on camphor. A hundred grains of camphor were digested in an ounce of concentrated sulphuric acid 1.000 = 1.250 = 1.000 11.60 8.625 100.00 As an internal medicine, camphor has been frequently employed in doses of from 5 to 20 grains, with much advantage; to procure sleep in mania, and to counteract gangrene. Though a manifest stimulant, when externally applied, it appears from the reports of Cullen and others, rather to diminish the animal temperature and the frequency of the pulse. In large doses it acts as a poison, an effect best counteracted by opium. It is administered to alleviate the irritating effects of cantharides, mezereon, the saline preparations of mercury and drastic purgatives. It lessens the nauseating tendency of squill, and prevents it from irritating the bladder. It is employed externally as a discutient.* Dissolved in acetic acid, with some essential oils, it forms the aromatic vinegar, for which we are indebted to the elder Mr. Henry. It remarkably promotes the solution of copal. Its effluvia are very noxious to insects, on which account it is much used to defend subjects of natural history from their ravages. * CANCER, MATTER OF. This morbid secretion was found by Dr. Crawford to give a green colour to sirup of violets, and A Scotch mutchkin, or 1-8th of a gallon of good seal oil, weighs 6010 gr. or 13 and 1-10th oz. avoirdupois, and lasts in a bright argand lamp, 11 hours 44 min. The weight of oil it consumes per hour, is equal to four times the weight of tallow in candles, 8 to the pound, and 3 1-7th times the weight of tallow in candles, 6 to the pound. But its light, being equal to that of 5 of the latter candles, it appears from the above table, that 2 pounds weight of oil, value 18. in an argand, are equivalent in illuminating pow. er to 3 pounds of tallow candles, which cost about three shillings. The larger the flame in the above candles, the greater the economy of light.* * CANNEL COAL. See COAL. * CANNON METAL. See COPPER.* *CANTHARIDES. Insects vulgarly called Spanish flies: lytta vesicatoria is the name adopted from Gmelin, by the London college. This insect is two-thirds of an inch in length, one-fourth in breadth, oblong, and of a gold shining colour, with soft elytera or wing sheathes, marked with three longitudinal raised stripes, and covering brown membranous wings. An insect of a square form, with black feet, but possessed of no vesicating property, is sometimes mixed with the cantharides. They have a heavy disagreeable odour, and acrid taste. If the inspissated watery decoction of these insects be treated with pure alcohol, a solution of a resinous matter is obtained, which being separated by gentle evaporation to dryness, and submitted for some time to the action of sulphuric ether, forms a yellow solution. By spontaneous evaporation crystalline plates are deposited, which may be freed from some adhering colouring matter by alcohol. Their appearance is like spermaceti. They are soluble in boiling alcohol, but precipitate as it cools. 100 They do not dissolve in water. According to M. Robiquet, who first discovered them, these plates form the true blistering principle. They might be called VESICATORIN. Besides the above peculiar body, cantharides contain, according to M. Robiquet, a green bland oil, insoluble in water, soluble in alcohol; a black matter, soluble in water, insoluble in alcohol, without blistering properties; a yellow viscid matter, mild, soluble in water and alcohol; the crystalline plates; a fatty bland matter; phosphates of lime and magnesia; a little acetic acid, and much lithic or uric acid. The blistering fly taken into the stomach in doses of a few grains, acts as a poison, occasioning horrible satyriasis, delirium, convulsions, and death. Some frightful cases are related by Orfila, vol. i. part 2d. Oils, milk, sirups, frictions on the spine, with volatile liniment and laudanum, and draughts containing musk, opium, and camphorated emulsion, are the best antidotes.* CAOUTCHOUc. This substance, which has been improperly termed elastic gum, and vulgarly, from its common application to rub out pencil marks on paper, India rubber, is obtained from the milky juice of different plants in hot countries. The chief of these are the Jatropha elastica, and Urceola elastica. The juice is applied in successive coatings on a mould of clay, and dried by the fire or in the sun; and when of a sufficient thickness, the mould is crushed, and the pieces shaken out. Acids separate the caoutchouc from the thinner part of the juice at once by coagulating it. The juice of old plants yields nearly two-thirds of its weight; that of younger plants less. Its colour, when fresh, is yellowish white, but it grows darker by exposure to the air. The elasticity of this substance is its most remarkable property: when warmed, as by immersion in hot water, slips of it may be drawn out to seven or eight times their original length, and will return to their former dimensions nearly. Cold renders it stiff and rigid, but warmth restores its original elasticity. Exposed to the fire it softens, swells up, and burns with a bright flame. In Cayenne it is used to give light as a candle. Its solvents are ether, volatile oils, and petroleum. The ether, however, requires to be washed with water repeatedly, and in this state it dissolves it completely. Pelletier recommends to boil the caoutchouc in water for an hour; then to cut it into slender threads; to boil it again about an hour; and then to put it into rectified sulphuric ether in a vessel close stopped. In this way he says it will be totally dissolved in a few days, without heat, except the impurities, which will fall to the bottom, if ether enough be employed. Berniard says, the nitrous ether dissolves it better than the sulphuric. If this solution be spread on any substance, the ether evaporates very quickly, and leaves a coating of caoutchouc unaltered in its properties. Naphtha, or petroleum, rectified into a colourless liquid, dissolves it, and likewise leaves it unchanged by evaporation. Oil of turpentine softens it, and forms a pasty mass, that may be spread as a varnish, but is very long in drying. A solution of caoutchouc in five times its weight of oil of tur pentine, and this solution dissolved in eight times its weight of drying linseed oil by boiling, is said to form the varnish of airballoons. Alkalis act upon it so as in time to destroy its elasticity. Sulphuric acid is decomposed by it; sulphurous acid being evolved, and the caoutchouc converted into charcoal. Nitric acid acts upon it with heat; nitrous gas being given out, and oxalic acid crystallizing from the residuum. On distil. lation it gives out ammonia, and carburet. ted hydrogen. Caoutchouc may be formed into various articles without undergoing the process of solution. If it be cut into a uniform slip of a proper thickness, and wound spirally round a glass or metal rod, so that the edges shall be in close contact, and in this state be boiled for some time, the edges will adhere so as to form a tube. Pieces of it may be readily joined by touching the edges with the solution in ether: but this is not absolutely necessary, for, if they be merely softened by heat, and then pressed together, they will unite very firmly. If linseed oil be rendered very drying by digesting it upon an oxide of lead, and afterwards applied with a small brush on any surface, and dried by the sun or in the smoke, it will afford a pellicle of considerable firmness, transparent, burning like caoutchouc, and wonderfully elastic. A pound of this oil, spread upon a stone, and exposed to the air for six or seven months, acquired almost all the properties of caoutchouc: it was used to make catheters and bougies, to varnish balloons, and for other purposes. Of the mineral caoutchouc there are seral varieties: 1 Of a blackish-brown inclining to olive, soft, exceedingly compressible, unctuous, with a slightly aromatic smell. It burns with a bright flame, leaving a black oily residuum, which does not become dry. 2. Black, dry, and cracked on the surface, but, when cut into, of a yellowish-white. A fluid resembling pyrolignic acid exudes from it when recently cut. It is pellucid on the edges, and nearly of a hyacinthine red colour. 3. Similar to the preceding, but of a somewhat firmer texture, and ligneous appearance, from having acquired consistency in repeated layers. 4. Resembling the first variety, but of a darker colour, and adhering to gray calcareous spar, with some grains of galæna. 5. Of a liver-brown colour, having the aspect of the vegetable caoutchouc, but passing by gradual transition into a brittle bitumen, of vitreous lustre, and a yellowish colour. 6. Dull reddish-brown, of a spongy or cork-like texture, containing blackishgray nuclei of impure caoutchouc. Many more varieties are enumerated. One specimen of this caoutchouc has been found in a petrified marine shell en closed in a rock, and another enclosed in crystallized fluor spar. The mineral caoutchouc resists the ac tion of solvents still more than the vegetable. The rectified oil of petroleum affects it most, particularly when by partial burning it is resolved into a pitchy viscous substance. A hundred grains of a specimen analyzed in the dry way by Klaproth, afforded carburetted hydrogen gas 38 cubic inches, carbonic acid gas 4, bituminous cil 73 grains, acidulous phlegm 1.5, charcoal 6.25, lime 2, silex 1.5, oxide of iron 75, sulphate of lime .5, alumina .25. CARAT. See ASSAY. CARBON. When vegetable matter, particularly the more solid, as wood, is exposed to heat in close vessels, the volatile parts fly off, and leave behind a black porous. substance, which is charcoal. If this be suffered to undergo combustion in contact with oxygen, or with atmospheric air, much: the greater part of it will combine with the oxygen, and escape in the form of gas; leaving about a two-hundredth part, which consists chiefly of different saline and me tallic substances. This pure inflammable part of the charcoal is what is commonly called carbon; and if the gas be received. into proper vessels, the carbon will be found to have been converted by the oxy gen into an acid, called the carbonic. See ACID (CARBONIC). From the circumstance, that inflammable substances refract light, in a ratio greater than that of their densities, Newton inferred, that the diamond was inflammable. The quantity of the inflammable part of charcoal requisite to form a hundred parts of carbonic acid, was calculated by Lavoisier to be twenty-eight parts. From a careful experiment of Mr. Tennant, 27.6 parts of diamond, and 72.4 of oxygen, formed 100 of carbonic acid; and hence he inferred the identity of the diamond, and the inflammable part of charcoal. * Diamonds had been frequently consumed in the open air with burning glasses; but Lavoisier first consumed them in oxygen gas, and discovered carbonic acid to be the only result. Sir George Mackenzie showed, that a red heat, inferior to what melts silver, is sufficient to burn diamonds. They first enlarge somewhat in volume, and then waste with a feeble flame. M. Guyton Morveau was the first who dropped diamonds into melted nitre, and observed the formation of carbonic acid. From a number of experiments M. Biot has made on the refraction of different substances, he has been led to form a differ ent opinion. According to him, if the ele. ments of which a substance is composed be known, their proportions may be calculated with the greatest accuracy from their refractive powers. Thus he finds, that the diamond cannot be pure carbon, but requires at least one-fourth of hydrogen, which has the greatest refractive power of any substance, to make its refraction commensurate to its density. In 1809, Messrs. Allen and Pepys made some accurate researches on the combustion of various species of carbon in oxygen, by means of an elegant apparatus of their own contrivance. A platina tube traversing a furnace, and containing a given weight of the carbonaceous substance, was connected at the ends with two mercurial gasometers, one of which was filled with oxygen gas, and the other was empty. The same weight of diamond, carbon, and plumbago, yielded very nearly the same volume of carbonic acid. Sir H. Davy was the first to show that the diamond was capable of supporting its own combustion in oxygen, without the continued application of extraneous heat, and he thus obviated one of the apparent anomalies of this body, compared with charcoal. This phenomenon, by his method, can now be easily exhibited. If the diamond, supported in a perforated cup, be fixed at the end of a jet, so that a stream of hydrogen can be thrown on it, it is easy, by inflaming the jet, to ig. nite the gem, and whilst in that state to introduce it into a globe or flask containing oxygen. On turning off the hydrogen, the diamond enters into combustion, and will go on burning till nearly consumed. The loss of weight, and corresponding production of carbonic acid, were thus beautifully shown. A neat form of apparatus for this purpose is delineated by Mr. Faraday, in the 9th volume of the Journal of Science. Sir. H. Davy found, that diamonds gave a volume of pure carbonic acid, equal to the oxygen consumed; charcoal and plumbago afforded a minute portion of hydrogen.* See DIAMOND. Well-burned charcoal is a conductor of electricity, though wood simply deprived of its moisture by baking is a non-conductor; but it is a very bad conductor of caloric, a property of considerable use on many occasions, as in lining crucibles. It is insoluble in water, and hence the utility of charring the surface of wood exposed to that liquid, in order to preserve it, a circumstance not unknown to the ancients. This preparation of timber has been proposed as an effectual preventive of what is commonly called the dry rot. It has an attraction, however, for a certain portion of water, which it retains very forcibly. Heated red-hot, or nearly so, it decomposes water; forming with its oxygen, carbonic acid, or carbonic oxide, according to the quantity present; and with the hydrogen a gaseous carburet, called carburetted hy. drogen, or heavy inflammable air. Charcoal is infusible by any heat. If exposed to a very high temperature in close vessels it loses little or nothing of its weight, but shrinks, becomes more compact, and acquires a deeper black colour. Recently prepared charcoal has a re markable property of absorbing different gases, and condensing them in its pores, without any alteration of their properties or its own. * The following are the latest results of M. Theodore de Saussure, with boxwood charcoal, the most powerful species: Gaseous ammonia, Carbonic oxide, Olefiant gas, Carbonic oxide, Oxygen, Azote, 90 vols. 85 65 55 40 35 35 9.42 9.25 7.5 Light gas from moist charcoal, 5.0 Hydrogen, 1.75 Very light charcoal, such as that of cork, absorbs scarcely any air; while the pit-coal of Rastiberg, sp. gr. 1.326, absorbs 10 times its volume. The absorption was always completed in 24 hours. This curious faculty, which is common to all porous bo |