[1] We deem an outline of the nature and effects of caloric as, in some respects, indispensably necessary; for caloric, it is to be observed, is an agent, whose effects are recognised in every species of fire-work.

[2] That the terms hot and cold are relative, as to our feelings, fact and observations abundantly prove. Dr. Fordyce (Phil. Trans. vol. 64 & 65) heated a room by stoves to two hundred and sixty degrees of Fahrenheit's scale, and remained in it for some time without great inconvenience. But different metallic substances, as the lock of the door, his watch and keys lying on the table, could not be touched without burning him: and although an egg became hard, and his pulse beat one hundred and thirty-nine per minute, yet a thermometer placed in his mouth was only two or three degrees hotter than common. He perspired profusely. Jenning's steam bath will heat the air in contact with the naked body from one hundred to one hundred and twenty degrees, a heat sufficient, as it is in the aqueous vapour, resulting from the combustion of alcohol or strong spirit, to induce a copious diaphoresis in less than half an hour. Having tried this experiment in several cases, I can only say, that I effected in the course of an hour, what, under ordinary circumstances, would require twelve or twenty-four, viz. a copious perspiration, and that too without the exhibition of sudorifics. The practice is an old one not only among civilized nations, but aborigines. It is nevertheless worthy of adoption.

Frozen mercury cannot be touched without experiencing a sensation similar to that of an ignited body, although directly opposite to heat.

[3] A writer of the last century remarks, that "he cannot possibly admit the sun to possess the least manner of heat, but rather to contain the capabilities of fire, like a stick, or a flint, though with a faculty of expressing it, by its own action, which the others have not. I imagine its beams not to be hot, in their rectilineal direction, but productive of this effect, from reflection, only. If the rays of the sun were fire, in the first instance, those consequences would naturally follow, that our friend and correspondent Tria so well describes in his Day of Judgment, 'The rivers were dried up, and liquid ore supplied their burning channels. The clouds were turned to fire, and shot through the astonished sky. The air was flame, and breathing was no more. The firmament was melted down, and rained its sulphur o'er the prostrate globe, &c.' The sun emanates light only, in the direct line, but owes its heat to reflection. We feel it, therefore, more intensely, in a valley, than on a hill. Why are the Alps and Pyrennees crowned with eternal frosts, while the shepherds, with their flocks, are sheltering their scorching heads from the heat of the sun, at the foot of them? Why do the upper regions of the air shower down their hail and snow, to be thawed and melted here below? Why shall a lens of ice receive the rays above, so coldly, and transmit them so intensely hot, beneath? Why is it warmer, in summer, though the sun is farther off, than in winter, when 'tis so much nearer to us? Because of our situation, in regard to it, only. In the first case the rays are vertical, in others lateral; and perpendicular reflections are stronger, than oblique ones. We judge of fire above, from what we feel below, &c."

The summit of Ætna, notwithstanding the fire of the volcano, is covered almost all the year with snow. Fazello, speaking of this says, that "this region extends nearly twelve miles; and, even in summer, is almost perpetually covered with snow, and extremely cold: which is the more wonderful as the summit continually produces, nourishes, and pours forth flames amid the ice and snow with which it is enveloped." Solinus says, "Ætna, in a wonderful manner, exhibits snows mixed with fires; and retains every appearance of the severest winter, amid her vast conflagrations."

Silius Italicus, and Claudian, and Pindar, who lived 500 years before the Christian era, bear testimony to the antiquity of this fact.

Silius Italicus, from the Latin.

Claudian, from the Latin.

Pindar, from the Greek.

The height of Ætna is generally estimated at 11,000 feet above the sea. In 1755, it issued out a torrent, not of mud, as was supposed, but of snow and ice melted by the lava. The same thing happened at the volcano of Cargarossa in South America.

The celebrated Herschel, (Phil. Trans. 1801, and Nich. Jour. 1. 13), in considering the construction of the sun, infers it to be a habitable globe more magnificent than our earth, or other planets, and that its lucid substance is not a liquid nor an elastic fluid; but that it exists in the manner of luminous clouds, swimming in the transparent atmosphere of the sun, or rather of lucid decompositions taking place within that atmosphere. The Philosophical Transactions, 1795, p. 72, also contains remarks on this lucid matter. Having rejected the old terms of spots, nuclei, penumbrÆ, and luculi, he has substituted those of openings, shallows, ridges, nodules, corrugations, indentations, and pores. The openings are places where the luminous solar clouds are removed, which he thinks are produced by a wind or gas from the sun's body. Shallows are depressions below the luminous clouds, and are caused by the propelling gas, which produces the openings. They are tufted like masses of clouds. Ridges are elevations of the luminous clouds. The length of one of the longest was found to be 75,000 miles. They generally surround the openings. Herschel thinks it probable, from appearances, that the luminous matter is disturbed at top by the transparent elastic fluid, which issues from the openings. Nodules are small elevations of the luminous matter. Corrugations are smaller elevations and depressions of the same matter. Indentations are the dark places of corrugations. That they are not much depressed, is deduced from their visibility near the margin of the sun. They are of the same nature as shallows, and of different sizes. Pores are the low places of indentations. The doctor is of opinion, that the phenomena before described could not appear, if the shining matter were a liquid; because, by the laws of hydrostatics, the openings, shallows, indentations, and pores would be filled up. Still less could these phenomena exist with the supposition of elastic fluidity. The shining matter, he concludes, must exist in the manner of empyreal luminous or phosphoric clouds. The planetary atmosphere of the sun, its great height, its density, as inferred from the power of gravitation, which is known to be twenty-seven times stronger at the sun's surface than with us, and other subjects are also discussed. He supposes the gas to pass from the sun itself upwards to the region of the clouds, so as to generate pores, corrugations, &c. He concludes finally, that if this view of the solar appearances be well founded, there will be no difficulty in ascertaining the actual state of the sun with regard to its energy in giving heat and light.

In a paper on the "Construction of the Heavens," the doctor thinks it probable, that the great stratum called the milky way is that in which the sun is placed, though perhaps not in the centre of its thickness. The celebrated astronomer Lalande supposes the spots before mentioned to be parts of the solid body of the sun, but admits not a luminous atmosphere, but a luminous ocean. For the observations of Dr. Young, see his Natural Philosophy, and of sir Isaac Newton, his Principia, &c. Consult also Biot.

Sir Isaac Newton has asserted, according to Nicholson, (British Encyclopedia) "that the density of the sun's heat, which is proportioned to his light, is seven times as great in Mercury as with us, and that water there would be all carried off in the shape of steam, for, he found, by experiments with the thermometer, that a heat seven times greater than that of the sun's beams in summer will serve to make water boil." That fixed stars are of the same nature as the sun, since they agree with it in several particulars, as in the property of emitting light continually, and in retaining constantly their relative situation with but little variation, is generally admitted. They are supposed also to emit heat as well as light. The sun is, therefore, considered a fixed star comparatively near us, and the fixed stars, which seem as centres to other systems of worlds, as suns at immense distances from us. Taking the distance of the sun from us to be, as is found by calculation, 95,000,000 miles, we may infer, that every thing must be scorched up at its surface; but this question is put at rest, if we consider that the sun's rays act on a calorific medium, as the cause of changing quiescent into distributable heat. May not light itself, by some process unknown to us, produce calorific rays? That heat and light are both material, and possess some properties in common, that for instance, of reflection and refraction, are facts well known; but to account for the peculiar agency of light, if it be admitted, is a problem, which, perhaps, will never be settled?

[4] Fire must have been a very potent instrument in the hands of Hannibal, if we believe what Livy and Pliny assert respecting the means he employed in crossing the Alps, which took him fifteen days, after meeting with almost every obstacle. Livy tells us, that Hannibal softened the rock by pouring vinegar upon it, after it had first been made hot under flaming piles of huge trees! M. Rollin quotes Pliny to prove that vinegar has the force to break stones and rocks! This story is altogether fabulous; for in the first place, had he vinegar sufficient; and, secondly, who ever knew that vinegar had force, or even the power of dissolving primitive rocks, such as granite or gneiss; and, thirdly, if it possessed the power stated by Pliny, and had he a sufficient quantity, where was his wood? For Polybius assures us, that Hannibal had no wood to make a fire with, and that there was not a tree in the place, where he then was, nor near it. That Hannibal passed over the Alps into Italy, and at an inclement season of the year, is certain, and that it was one of the greatest achievements that an enterprising commander ever accomplished, is generally admitted.

[5] Respiration is a mechanical and chemical process, and consists in alternate inhalation and exhalation, which, in consequence of the oxygen gas in the air, effects a change in the venous blood that enters the lungs from the pulmonary artery. Now as this blood is charged with carbon, to which its dark purple colour is owing, it is carried off in union with oxygen in the form of carbonic acid. Hence carbonic acid is produced in respiration and the venous blood is changed into the bright red arterial blood. A common sized man will consume about 46 thousand cubic inches of oxygen per diem; equivalent to 125 cubic feet of air, and makes about twenty respirations in a minute, or for every seven pulsations breathes twice.

[6] Of this fact the reader may form some idea, when he is informed, that Newton's Principia, Biot's Physique, Hatchette, Gregory, &c. &c. form the class books of instruction, works which require deep study, and profound thought.

[7] Various applications of chemistry, among which that to gunpowder, drew my attention at an early period of life. In the Aurora of Philad. I published a series of essays on this and other subjects, which, from the letters received at that time, I flatter myself tended in some degree to advance the manufacturing interest in the United States; an interest, which is connected with our individual and national prosperity, and the permanent and practical independence of the republic. These essays were entitled "Application of chemistry to the arts and manufactures," and published in 1808. I have since enlarged that plan in the Artist's Manual, &c. 2 vols. 8vo. While noticing this subject we may add, that, having the honour of being one of the few of the original society of Philadelphia for the promotion of National Industry, whose essays excited, as they claimed, the attention of the citizens of the United States, much is due to the indefatigable labours of some of the members of that association. We are greatly indebted to the able and masterly pen of Samuel Jackson M. D. Professor of Pharmacy in the college of Apothecaries, of Philadelphia, for many of the best essays it produced, whose disinterested motives, liberal and exalted mind, and pure patriotic feeling prompted him to the laudable undertaking; and whose essays were full, clear, and comprehensive. Viewing his talents, his worth, his merit, we may truly add, that he is not only an honour to the country which gave him birth, but an ornament to the age in which he lives. The able address of the Philadelphia LinnÆan society, penned and signed by him, the late Samuel Benezet M. D., and the author, as a committee, although written many years ago, contains the principles, which are now advocated for the support and encouragement of national industry. This address was calculated, however, to promote, at the same time, the interests of Natural History.

[8] Incombustible cloth made of this substance was formerly in use, not only for domestic purposes, but, also to retain the ashes of the dead from those of the funeral pile. Cloth made of amianthus, when greased, or soiled, may be cleansed by throwing it into a bright fire. It is then restored to a dazzling white colour. Pliny, the naturalist, saw table cloths, towels, and napkins of amianthus taken from the table of a great feast, thrown into the fire, and burnt before the whole company; and by this operation, he says, they became better cleansed than if they had been washed.

Pontoppidan (Natural History of Norway) remarks, that he has a piece of paper made of the Norway asbestus, which, when thrown into a fierce fire, is not in the least wasted, but what is written on it totally disappears. In Norway, the stone flax is prepared by beating it in water, till the fibres separate, which are repeatedly washed, and then dried in a sieve. It is afterwards spun, observing to moisten the fingers with oil.

[9] In the year 1601, a horse, which had been taught to perform a number of tricks, was tried, as possessed by the devil, and condemned to be burnt. Joblonski affirms in his Lexicon, &c. that he was condemned to the flames in Lisbon. Nothing was a greater imposition on mankind than the Oracles. The imposition of causing statues to speak, as the head of Orpheus in the island of Lesbos, the Æsculapius of Alexander, &c. may be readily perceived, when Lucius relates, that, in the case of Alexander's oracle, he took instead of a pipe, the gullet of a crane, and transmitted the voice through it to the mouth of the statue! Bishop Theophilus, in the fourth century, broke to pieces the statues at Alexandria. He found some which were hollow, and placed in such a manner against a wall, that a priest could slip unperceived behind them, and speak to the ignorant populace through their mouths. Professor Beckman observes, "that the Pagan priests, like our jugglers, were afraid that their deceptions, if long practised, might be discovered. They considered it, therefore, as more secure to deliver the answers themselves, or cause them to be delivered by women instructed for that purpose, or by writings, or by any other means. We read, nevertheless, that idols, and the images of saints once spoke; for at present the latter will not venture to open their mouths. If their votaries ever really heard a voice proceed from the statue, it may have been produced in the before-mentioned manner." We think, that a contrivance, similar to the bull of Phalaris, in the place of hollow statues, would furnish a good reality.

The oracle of Apollo at Delphos, says Percy, having been consulted about the manner of stopping a plague then raging at Athens, returned for answer, that the plague should cease, when Apollo's altar, which was cubical, should be doubled. The philosophers of Athens immediately applied themselves to discover the duplicature of the cube, which henceforward was called the Delian Problem, and continued for a long time to be an object of the keenest pursuit to the curious. The first who discovered the solution was Hippocrates Chias.

[10] Signs in the heavens were believed by the ancients; and even with regard to natural occurrences, they produced melancholy and awful reflections. Augustus CÆsar was so afraid of thunder and lightning, that, though he carried about him a skin of a sea-calf, which was in those days accounted an excellent paratonnerre, yet, whenever he saw a tempest coming, he used to fly for refuge to some vaulted place underground. Caius Caligula rivalled Augustus in this respect; for Suetonius observes, that when it thundered, he would wrap his head in some covering; or, if in bed, leap out of bed and hide himself under it.

[11] By means of a solar microscope, I have seen the animalcula in vinegar several inches in length, some of which had the appearance of eels, and in motion.

[12] There is a sort of mountebanks not only in Ceylon, but in many other parts of the East Indies, who make a trade of taming serpents, which they pretend to do by incantation, and carry them about by way of show. I once witnessed the taming of a serpent, a black snake about four feet in length, by an English gentleman at Harrowgate, in the neighbourhood of Philadelphia. He was remarkably fond of snakes for pets, and had them not only to follow him, but also to be about in the house among his children, who became familiar with them; and, although young myself, I observed that they were passive and obedient, and knew by instinct their dependence on his favours.

The incantation, that Mr. C—d used, was simply this: The snake was put into a room, and Mr. C. took in with him a bowl of milk, and the door was closed. Having taken off his coat, and put on a glove, he proceeded towards his antagonist, who, being prepared for the attack, made at him, but was repulsed; a second and third attempt was made, but he was thrown back as before. The snake finding himself mastered, did not think proper to renew the combat, and crawled into the corner panting for breath. Mr. C. now took some of the milk and placed it before him, without the least fear, and after he had finished it, he gave him more. This he continued until the snake was satisfied. After which, to the astonishment of all who witnessed the experiment, he took it up, and having wound itself round his arm, he carried it home. Whether he examined his mouth, destroyed the fang, or the vesicular sac, (if it had one), I do not recollect; but this same snake was afterwards a great favorite, and would follow his master like a dog, and even play about with the children. I mention this incident to show, that serpents possess considerable instinct, and are, like domestic animals, conscious of their friends and benefactors, and may be trained in the same manner.

In the island of Ceylon, there is a small animal called the Indian Ichneumon, which destroys snakes in abundance; but, what is remarkable, he only attacks them in an open place, where he has an opportunity of running to a certain herb, which he knows instinctively to be an antidote against the poison of the bite, if he should happen to receive one. The monkeys of India, knowing the malignity of snakes, make a business of hunting and destroying them at night; after seizing them, they carry them to a stone, and beat their heads until the fangs are destroyed, and then exultingly throw them in the air. The poison is lodged in two small vesicles, and when the animal bites they are squeezed, and the poison is forced through the fangs into the wound. If the vesicles be extracted, or the liquid prevented from flowing into the wound, the bite is harmless.

[13] The great cave on Crooked Creek, was discovered about the year 1800, by Mr. Baker. He proceeded only a small distance into it. On the succeeding day, he brought his wife, and two or three children to explore it. He carried a torch, which he accidentally dropped. During two days and two nights, this family wandered in total darkness, though sometimes within the hearing of a cataract, when, fortunately, Mrs. Baker, in attempting to support herself on a rock, perceived that it was wet. She conjectured that it was caused by the mud, which they had brought in upon their feet. Baker immediately ascended the rock, and saw the light of day.

[14] There can be no doubt, as we observed, that miasma is variously compounded; but there is no certainty, as to what it is composed of, or what modifications it may assume. That it is, however, a chemical combination, and may be decomposed, and destroyed by chemical agents, appears equally true. The disinfecting apparatus of Morveau, sundry fumigations, &c. are used for this purpose. The proper destroyers of these gaseous poisons, are nitric acid vapour, muriatic acid, and chlorine. The two last are the most effectual. How would chlorine gas act on prussine gas, or cyanogen? Would it not deprive it of its carbon, forming the chlorocarbonic acid, and thus set the azote at liberty, or might it not unite with the nitrogen, and form a chloride of nitrogen? Suppose the cyanogen to be combined with hydrogen, the decomposition of the hydrocyanic acid would be effected first by the chlorine combining with the hydrogen, forming muriatic acid, and secondly with the carbon, forming chlorocarbonic acid. If hydrogen, in any other combination, should exist, would not the chlorine in every case decompose such compound, and thereby destroy its deletereous properties by taking away its hydrogen? I think it will be proved, some time or other, that the miasma, which produces yellow fever, is a compound of carbon and azote, with hydrogen, acting under particular circumstances and conditions.

Various other means, besides those we have stated, have been recommended to prevent the effect of contagious matter, such as odoriferous substances, preparations of camphor, aromatic vinegar, called the vinegar of four thieves, &c. but all come short of the effect, and may be regarded as nostrums. The vapour of burning sulphur, or sulphurous acid, is used in the East against the plague; but this is inferior to either of the other acids, of which chlorine, formerly called oxymuriatic acid, is to be preferred. A mixture of four parts of common salt, one of black oxide of manganese, and two of sulphuric acid, or muriatic acid poured on manganese or red lead, will generate chlorine gas. Morveau's disinfecting apparatus contains the above mixture. The free use of this gas in apartments, &c. &c. cannot be too strongly recommended.

[15] On this subject, see a paper by Mr. Howard in the English Philosophical Transactions, for 1802, and by Vauquelin in the Journal des Mines, No. 76.

[16] For the history of saltpetre, the reader may consult, with advantage, Beckman's History of Inventions.

[17] "The affinity of charcoal for oxygen is so considerable, that instances have been known of its undergoing spontaneous combustion by simple contact with the air. An occurrence of this kind took place at the powder mills of Essonne, in France. (An. de Chim. 36, p, 93.) A large quantity of recently burnt charcoal had been ground in the usual manner, and was deposited in a large receptacle for future use; some days after, the door of the magazine being opened, in order to remove a part of the charcoal, an extraordinary heat was perceived, and immediately a train of fire was observed, spreading over the surface of the charcoal, and which was not extinguished without much difficulty." Aikin's Chemical Dictionary, vol. i, p. 238.

[18] This apparatus will heat the air in a room to 84° in the coldest weather, and is particularly calculated for cotton mills, and other purposes. His invention is considered to be a judicious application of a well known principle. Count Rumford heated rooms in a similar manner by steam, which may be seen in the Repository of Arts vol. xv, p. 186. A Mr. Green of Wandsworth, England, obtained a patent in 1793, for warming rooms, by heated air, heated with steam. Steam pipes, however, are now in use in the United States. In consequence of the great quantity of latent caloric in steam (about 1000 degrees) which is given out as free heat in its condensation, this principle has been judiciously applied not only to the warming of apartments, but to the boiling of dye kettles, and other purposes. See an account of Woolf's steam apparatus, subsequent pages.

[19] The principal workmen they describe, are a master powderer, a master carpenter, a master cooper, a head boy, (GarÇon) employed in the pulverization of the substances, another for the fabrication of charcoal, one for every mill, besides workmen for aiding in the charring, for the mill, &c.

[20] TraitÉ sur l'art de fabriquer la poudre À canon, par MM. BottÉe et Riffault may be consulted.

[21] This is a mixed gas, composed of carburetted hydrogen, and carbonic oxide.

[22] His son wrote a work, having the following title: "Thoughts concerning that last and most perfect work of nature, and chief of metals, gold, its wonderful properties, generation, affection, effects, and fitness for the operations of art; illustrated by experiments," from the Latin. Hamburgh, 1685, 8vo.

[23] In the year 1777, Lord Mahon, afterwards Earl Stanhope, exhibited some experiments, to prove the certain, cheap, and simple method of securing houses against fire, without making use of either brick, stones, tiles, iron, or any such incombustible material. A building, entirely constructed of wood, and of lath and plaster, with a very small quantity of sand laid under the floors, which were of deal, was attempted to be set on fire by means of a large quantity of dry burning fuel, faggots, straw, pitch and other combustibles, with which the lower room of this building was filled, from the floor to the ceiling almost in every part. The whole mass of fire burnt out without doing the least damage. Those who were in the next story, directly over the conflagration, did not perceive the least degree of heat. A wooden stair case, made in the same manner, also resisted the flames.

[24] The imitation of thunder, rain, hail, &c. for theatrical purposes, is variously performed. Mr. Nicholson, in describing an exhibition he saw in London, (See Phantasmagoria,) remarks, that thunder was imitated very accurately, by means of sheet iron plates. The noise of rain and hail may be imitated by procuring a thin hollow cylinder of wood, about ten inches wide, and two or three feet long; dividing its inside into five equal parts, by boards, placed obliquely, of five or six inches, observing to let there be between them and the wooden circle, a space of about one-sixth of an inch, and then introducing about four or five pounds of shot, and turning it upside down. The shot will pass through the various partitions, and resemble the fall of rain. If large shot be used, the noise will be increased, and resemble hail.

According to the Dictionnaire de l'Industrie, (article Tonnerre artificiel), thunder is imitated, by making a hexangular case of sheet iron, and putting stones or small balls into it, and rolling it more or less swiftly. Another mode is to roll cannon balls on a floor, on which is loosely nailed, at certain distances apart, strips of wood or lath. A clap of thunder is imitated by letting fall on each other, very suddenly, a number of sheet iron plates, having them previously suspended, or strung on a cord, which must be vertical. In 1784, M. Michael, (Journal de Paris) made a machine, which imitated thunder, so completely, as either to produce the most violent clap, or the most distant rumbling, with intermediate variations. Parchment, stretched over a frame, has likewise, been used for the same purpose. The distant thunder may be represented in this manner; but, to produce a sharp noise, or clap, something more is required.