M. Maillardet has constructed various other automata, representing

insects and other animals. One of these was a spider entirely made of steel, which exhibited all the movements of the animal. It ran on the surface of a table during three minutes, and to prevent it from running off, its course always tended towards the centre of the table. He constructed likewise a caterpillar, a lizard, a mouse, and a serpent. The serpent crawls about in every direction, opens its mouth, hisses, and darts out its tongue. Ingenious and beautiful as all these pieces of mechanism are, and surprising as their effects appear even to scientific spectators, the principal object of their inventors was to astonish and amuse the public. We should form an erroneous judgment, however, if we suppose that this was the only result of the ingenuity which they displayed. The passion for automatic exhibitions, which characterized the 18th century, gave rise to the most ingenious mechanical devices, and introduced among the higher orders of artists habits of nice and accurate execution in the formation of the most delicate pieces of machinery. The same combination of the mechanical powers which made the spider crawl, or which waved the tiny rod of the magician, contributed in future years to purposes of higher import. Those wheels and pinions, which almost eluded our senses by their minuteness, re-appeared in the stupendous mechanism of our spinning-machines and our steam-engines. The elements of the tumbling-puppet were revived in the chronometer, which now conducts our navy through the ocean; and the shapeless wheel which directed the hand of the drawing automaton has served, in the present age, to guide the movements of the tambouring engine. Those mechanical wonders, which in one century enriched only the conjuror who used them, contributed in another to augment the wealth of the nation; and those automatic toys, which once amused the vulgar, are now employed in extending the power and promoting the civilization of our species. In whatever way, indeed, the power of genius may invent or combine, and to whatever low or even ludicrous purposes that invention or combination may be originally applied, society receives a gift which it can never lose; and though the value of the seed may not be at once recognized, and though it may lie long unproductive in the ungenial till of human knowledge, it will some time or other evolve its germ, and yield to mankind its natural and abundant harvest. Did the limits of so popular a volume as this ought to be permit it, I should have proceeded to give a general description of some of these extraordinary pieces of machinery, the construction and effects of which never fail to strike the spectator with surprise. This, however, would lead me into a field too extensive, and I shall therefore confine myself to a notice of three very remarkable pieces of mechanism which are at present very little known to the general reader, viz., the tambouring machine of Mr. Duncan, the statue-turning machine of Mr. Watt, and the calculating machinery of Mr. Babbage. The tambouring of muslins, or the art of producing upon them ornamental flowers and figures, has been long known and practised in Britain as well as in other countries; but it was not long before the year 1790, that it became an object of general manufacture in the west of Scotland, where it was chiefly carried on. At first it was under the direction of foreigners; but their aid was not long necessary, and it speedily extended to such a degree as to occupy, either wholly or partially, more than 20,000 females. Many of these labourers lived in the neighbourhood of Glasgow, which was the chief seat of the manufacture; but others were scattered through every part of Scotland, and supplied by agents with work and money. In Glasgow, a tambourer of ordinary skill could not in general earn more than five or six shillings a week by constant application; but to a labouring artisan, who had several daughters, even these low wages formed a source of great wealth. At the age of five years, a child capable of handling a needle was devoted to tambouring, even though it could not earn more than a shilling or two in a week; and the consequence of this was, that female children were taken from school, and rendered totally unfit for any social or domestic duty. The tambouring population, was, therefore, of the worst kind, and it must have been regarded as a blessing rather than as a calamity, when the work which they performed was entrusted to regular machinery. Mr. John Duncan of Glasgow, the inventor of the tambouring machinery, was one of those unfortunate individuals who benefit their species without benefiting themselves, and who died in the meridian of life, the victim of poverty and of national ingratitude. He conceived the idea of bringing into action a great number of needles at the same time, in order to shorten the process by manual labour; but he at first was perplexed about the diversification of the pattern. This difficulty, however, he soon surmounted by employing two forces at right angles to each other, which gave him a new force in the direction of the diagonal of the parallelogram, whose sides were formed by the original forces. His first machine was very imperfect; but after two years’ study, he formed a company, at whose expense six improved machines were put in action, and who secured the invention by a patent. At this time the idea of rendering the machine automatic had scarcely occurred to him; but he afterwards succeeded in accomplishing this great object, and the tambouring machines were placed under the surveillance of a steam-engine. Another patent was taken for these improvements. The reader who desires to have a minute account of these improvements, and of the various parts of the machinery, will be amply gratified by perusing the inventor’s own account of the machinery in the article CHAINWORK in the Edinburgh Encyclopædia. At present it will be sufficient to state, that the muslin to be tamboured was suspended vertically in a frame, which was capable of being moved both in a vertical and a horizontal direction. Sixty or more needles lying horizontally occupied a frame in front of the muslin web. Each of these working needles, as they are called, was attended by a feeding-needle, which, by a circular motion round the working-needle, lodged upon the stem of the latter the loop of the thread. The sixty needles then penetrated the web, and, in order that they might return again without injuring the fabric, the barb or eye of the needle, which resembled the barb of a fishing-hook, was shut by a slider. The muslin web then took a new position by means of the machinery that gave it its horizontal and vertical motion, so that the sixty needles penetrated it, at their next movement, at another point of the figure or flower. This operation went on till sixty flowers were completed. The web was then slightly wound up, that the needles might be opposite that part of it on which they were to work another row of flowers. The flowers were generally at an inch distance, and the rows were placed so that the flowers formed what are called diamonds. There were seventy-two rows of flowers in a yard, so that in every square yard there were nearly 4000 flowers, and in every piece of ten yards long 40,000. The number of loops or stitches in a flower varied with the pattern, but on an average there were about thirty. Hence the number of stitches in a yard were 120,000, and the number in a piece is 1,200,000. The average work done in a week by one machine was fifteen yards, or 60,000 flowers, or 1,800,000 stitches; and by comparing this with the work done by one person with the hand, it appeared that the machine enabled one person to do the work of twenty-four persons. One of the most curious and important applications of machinery to the arts which has been suggested in modern times, was made by the late Mr. Watt, in the construction of a machine for copying or reducing statues and sculpture of all kinds. The art of multiplying busts and statues, by casts in plaster of Paris, has been the means of diffusing a knowledge of this branch of the fine arts; but from the fragile nature of the material, the copies thus produced were unfit for exposure to the weather, and therefore ill calculated for ornamenting public buildings, or for perpetuating the memory of public achievements. A machine, therefore, which is capable of multiplying the labours of the sculptor in the durable materials of marble or of brass was a desideratum of the highest value, and one which could have been expected only from a genius of the first order. During many years Mr. Watt carried on his labours in secret, and he concealed even his intention of constructing such a machine. After he had made considerable progress in its execution, and had thought of securing his invention by a patent, he learned that an ingenious individual in his own neighbourhood had been long occupied in the same pursuit; and Mr. Watt informed me that he had every reason to believe that this gentleman was entirely ignorant of his labours. A proposal was then made that the two inventors should combine their talents, and secure the privilege by a joint patent; but Mr. Watt had experienced so frequently the fatal operation of our patent laws, that he saw many difficulties in the way of such an arrangement, and he was unwilling, at his advanced age, to embark in a project so extensive, and which seemed to require for its successful prosecution all the ardour and ambition of a youthful mind. The scheme was therefore abandoned; and such is the unfortunate operation of our patent laws, that the circumstance of two individuals having made the same invention has prevented both from bringing it to perfection, and conferring a great practical benefit upon their species. The machine which Mr. Watt had constructed had actually executed some excellent pieces of work. I have seen in his house at Heathfield copies of basso-relievos, and complete statues of a small size; and some of his friends have in their possession other specimens of its performance. Of all the machines which have been constructed in modern times, the calculating-machine is doubtless the most extraordinary. Pieces of mechanism for performing particular arithmetical operations have been long ago constructed, but these bear no comparison either in ingenuity or in magnitude to the grand design conceived and nearly executed by Mr. Babbage. Great as the power of mechanism is known to be, yet we venture to say, that many of the most intelligent of our readers will scarcely admit it to be possible that astronomical and navigation tables can be accurately computed by machinery; that the machine can itself correct the errors which it may commit; and that the results of its calculations, when absolutely free from error, can be printed off, without the aid of human hands, or the operation of human intelligence. All this, however, Mr. Babbage’s machine can do; and as I have had the advantage of seeing it actually calculate, and of studying its construction with Mr. Babbage himself, I am able to make the above statement on personal observation. The calculating machine now constructing under the superintendence of the inventor has been executed at the expense of the British Government, and is of course their property. It consists essentially of two parts; a calculating part, and a printing part, both of which are necessary to the fulfilment of Mr. Babbage’s views; for the whole advantage would be lost if the computations made by the machine were copied by human hands and transferred to types by the common process. The greater part of the calculating machinery is already constructed, and exhibits workmanship of such extraordinary skill and beauty, that nothing approaching to it has been witnessed. In order to execute it, particularly those parts of the apparatus which are dissimilar to any used in ordinary mechanical constructions, tools and machinery of great expense and complexity have been invented and constructed; and in many instances contrivances of singular ingenuity have been resorted to which cannot fail to prove extensively useful in various branches of the mechanical arts. The drawings of this machinery, which form a large part of the work, and on which all the contrivance has been bestowed, and all the alterations made, cover upwards of 400 _square feet of surface_, and are executed with extraordinary care and precision. In so complex a piece of mechanism, in which interrupted motions are propagated simultaneously along a great variety of trains of mechanism, it might have been supposed that obstructions would arise, or even incompatibilities occur, from the impracticability of foreseeing all the possible combinations of the parts; but this doubt has been entirely removed, by the constant employment of a system of mechanical notation invented by Mr. Babbage, which places distinctly in view, at every instant, the progress of motion through all the parts of this or any other machine, and by writing down in tables the times required for all the movements, this method renders it easy to avoid all risk of two opposite actions arriving at the same instant at any part of the engine. In the printing part of the machine less progress has been made in the actual execution than in the calculating part. The cause of this is the greater difficulty of its contrivance, not for transferring the computations from the calculating part to the copper or other plate destined to receive it, but for giving to the plate itself that number and variety of movements which the forms adopted in printed tables may call for in practice. The practical object of the calculating engine is to compute and print a great variety and extent of astronomical and navigation tables, which could not be done without enormous intellectual and manual labour, and which, even if executed by such labour, could not be calculated with the requisite accuracy. Mathematicians, astronomers, and navigators, do not require to be informed of the real value of such tables; but it may be proper to state, for the information of others, that _seventeen_ large folio volumes of logarithmic tables alone were calculated, at an enormous expense, by the French Government; and that the British Government regarded these tables to be of such national value, that they proposed to the French Board of Longitude to print an _abridgement_ of them at the joint expense of the two nations, and offered to advance 5000_l._ for that purpose. Besides logarithmic tables, Mr. Babbage’s machine will calculate tables of the powers and products of numbers, and all astronomical tables for determining the positions of the sun, moon, and planets; and the same mechanical principles have enabled him to integrate innumerable equations of finite differences, that is, when the equation of differences is given, he can, by setting an engine, produce at the end of a given time any distant term which may be required, or any succession of terms commencing at a distant point. Besides the cheapness and celerity with which this machine will perform its work, the _absolute accuracy_ of the printed results deserves especial notice. By peculiar contrivances, any small error produced by accidental dust, or by any slight inaccuracy in one of the wheels, is corrected as soon as it is transmitted to the next, and this is done in such a manner as effectually to prevent any accumulation of small errors from producing an erroneous figure in the result. In order to convey some idea of this stupendous undertaking, we may mention the effects produced by a small trial engine constructed by the inventor, and by which he computed the following table from the formula _x^2_ + _x_ + 41. The figures, as they were calculated by the machine, were not exhibited to the eye as in sliding-rules and similar instruments, but were actually presented to the eye on two opposite sites of the machine, the number 383, for example, appearing in figures before the person employed in copying. _Table calculated by a small Trial Engine._ 41 131 383 797 1373 43 151 421 853 1447 47 173 461 911 1523 53 197 503 971 1601 61 223 547 1033 1681 71 251 593 1097 1763 83 281 641 1163 1847 97 313 691 1231 1933 113 347 743 1301 2021 While the machine was occupied in calculating this table, a friend of the inventor undertook to write down the numbers as they appeared. In consequence of the copyist writing quickly, he rather more than kept pace with the engine, but as soon as five figures appeared, the machine was at least equal in speed to the writer. At another trial _thirty-two_ numbers of the same table were calculated in the space of _two minutes and thirty seconds_; and as these contained _eighty-two_ figures, the engine produced thirty-three figures every minute, or more than one figure in every two seconds. On another occasion it produced _forty-four_ figures per minute. This rate of computation could be maintained for any length of time; and it is probable that few writers are able to copy with equal speed for many hours together. Some of that class of individuals who envy all great men, and deny all great inventions, have ignorantly stated that Mr. Babbage’s invention is not new. The same persons, had it suited their purpose, would have maintained that the invention of spectacles was an anticipation of the telescope; but even this is more true than the allegation that the arithmetical machines of Pascal and others were the types of Mr. Babbage’s engine. The object of these machines was entirely different. Their highest functions were to perform the operations of common arithmetic. Mr. Babbage’s engine, it is true, can perform these operations also, and can extract the roots of numbers, and approximate to the roots of equations, and even to their impossible roots. But this is not its object. Its function, in contradistinction to that of all other contrivances for calculating, is to embody in machinery the method of differences, which has never before been done; and the effects which it is capable of producing, and the works which in the course of a few years we expect to see it execute, will place it at an infinite distance from all other efforts of mechanical genius.[33] [33] A popular account of this engine will be found in Mr. Babbage’s interesting volume _On the Economy of Manufactures_, lately published. LETTER XII. Wonders of chemistry--Origin, progress, and objects of alchemy--Art of breathing fire--Employed by Barchochebas, Eunus, &c.--Modern method--Art of walking upon burning coals and red-hot iron, and of plunging the hands in melted lead and boiling water--Singular property of boiling tar--Workmen plunge their hands in melted copper--Trial of ordeal by fire--Aldini’s incombustible dresses--Examples of their wonderful power in resisting flame--Power of breathing and enduring air of high temperatures--Experiments made by Sir Joseph Banks, Sir Charles Blagden, and Mr. Chantrey. Chemistry has from its infancy been pre-eminently the science of wonders. In her laboratory the alchemist and the magician have revelled uncontrolled, and from her treasures was forged the sceptre which was so long and so fatally wielded over human reason. The changes which take place in the bodies immediately around us are too few in number and too remote from observation to excite much of our notice; but when the substances procured directly from nature, or formed casually by art, become objects of investigation, they exhibit in their simple or combined actions the most extraordinary effects. The phenomena which they display, and the products which they form, so little resemble those with which we are familiar, that the most phlegmatic and the least speculative observer must have anticipated from them the creation of new and valuable compounds. It can scarcely, therefore, be a matter of surprise that minds of the highest order, and spirits of the loftiest ambition, should have sought in the transmutations of chemistry for those splendid products which were conceived to be most conducive to human happiness. The disciple of Mammon grew pale over his crucible in his ardour to convert the baser metals into gold; the philosopher pined in secret for the universal solvent which might develop the elements of the precious stones and yield to him the means of their production; and the philanthropist aspired after a universal medicine, which might arrest disease in its course, and prolong indefinitely the life of man. To us, who live under the meridian of knowledge, such expectations must appear as presumptuous as they were delusive; but when we consider that gold and silver were actually produced by chemical processes from the rude ores of lead and copper--that some of the most refractory bodies had yielded to the disintegrating and solvent powers of chemical agents, and that the mercurial preparations of the Arabian physicians had operated like charms in the cure of diseases that had resisted the feeble medicines of the times, we may find some apology for the extravagant expectations of the alchemists. An object of lofty pursuit, even if it be one of impossible attainment, is not unworthy philosophical ambition. Though we cannot scale the summit of the volcanic cone, we may yet reach its heaving flanks; and though we cannot decompose its loftiest fires, we may yet study the lava which they have melted and the products which they have sublimed. In like manner, though the philosopher’s stone has not been found, chemistry has derived rich accessions from its search;--though the general solvent has not been obtained, yet the diamond and the gems have surrendered to science their adamantine strength;--and though the elixir of life has never been distilled, yet other medicines have soothed the “ills which flesh is heir to,” and prolonged in no slight degree the average term of our existence. Thus far the pursuits of the alchemist were honourable and useful; but when his calling was followed, as it soon was, by men prodigal of fortune and of character, science became an instrument of crime; secrets unattained were bartered for the gold of the credulous and the ignorant, and books innumerable were composed to teach these pretended secrets to the world. An intellectual reaction, however, soon took place; and those very princes who had sought to fill their exhausted treasuries at the furnace of the chemist, were the first to enact laws against the frauds which they had encouraged, and to dispel the illusions which had so long deceived their subjects. But even when the moral atmosphere of Europe was thus disinfected, chemistry supplied the magician with his most lucrative wonders, and those who could no longer delude the public with dreams of wealth and longevity, now sought to amuse and astonish them by the exhibition of their skill. The narrow limits of this volume will not permit me to give even a general view of those extraordinary effects which this popular science can display. I must therefore select from its inexhaustible stores those topics which are most striking in their results, and most popular in their details. One of the most ancient feats of magic was the art of breathing flame,--an art which even now excites the astonishment of the vulgar. During the insurrection of the slaves in Sicily, in the second century before Christ, a Syrian named Eunus acquired by his knowledge the rank of their leader. In order to establish his influence over their minds, he pretended to possess miraculous power. When he wished to inspire his followers with courage, he breathed flames or sparks among them from his mouth, at the same time that he was rousing them by his eloquence. St. Jerome informs us that the Rabbi Barchochebas, who headed the Jews in their last revolt against Hadrian, made them believe that he was the Messiah, by vomiting flames from his mouth; and at a later period, the Emperor Constantius was thrown into a state of alarm when Valentinian informed him that he had seen one of the body-guards breathing out fire and flames. We are not acquainted with the exact methods by which these effects were produced; but Florus informs us that Eunus filled a perforated nut-shell with sulphur and fire, and having concealed it in his mouth, he breathed gently through it while he was speaking. This art is performed more simply by the modern juggler. Having rolled together some flax or hemp, so as to form a ball the size of a walnut, he sets it on fire, and allows it to burn till it is nearly consumed: he then rolls round it while burning some additional flax, and by these means the fire may be retained in it for a considerable time. At the commencement of his exhibition he introduces the ball into his mouth, and while he breathes through it the fire is revived, and a number of burning sparks are projected from his mouth. These sparks are too feeble to do any harm, provided he inhales the air through his nostrils. The kindred art of walking on burning coals or red-hot iron remounts to the same antiquity. The priestesses of Diana at Castabala in Cappadocia were accustomed, according to Strabo, to walk over burning coals; and at the annual festival which was held in the temple of Apollo on Mount Soracte in Etruria, the Hirpi marched over burning coals, and on this account they were exempted from military service, and received other privileges from the Roman Senate. This power of resisting fire was ascribed even by Varro to the use of some liniment with which they anointed the soles of their feet. Of the same character was the art of holding red-hot iron in the hands or between the teeth, and of plunging the hands into boiling water or melted lead. About the close of the seventeenth century, an Englishman of the name of Richardson rendered himself famous by chewing burning coals, pouring melted lead upon his tongue, and swallowing melted glass. That these effects are produced partly by deception, and partly by a previous preparation of the parts subjected to the heat, can scarcely admit of a doubt. The fusible metal, composed of mercury, tin, and bismuth, which melts at a low temperature, might easily have been substituted in place of lead; and fluids of easy ebullition may have been used in place of boiling water. A solution of spermaceti or sulphuric ether, tinged with alkanet root, which becomes solid at 50° of Fahrenheit, and melts and boils with the heat of the hand, is supposed to be the substance which is used at Naples when the dried blood of St. Januarius melts spontaneously, and boils over the vessel which contains it. But even when the fluid requires a high temperature to boil, it may have other properties, which enable us to plunge our hands into it with impunity. This is the case with boiling tar, which boils at a temperature of 220°, even higher than that of water. Mr. Davenport informs us, that he saw one of the workmen in the Royal Dock-yard at Chatham immerse his naked hand in tar of that temperature. He drew up his coat-sleeves, dipped in his hand and wrist, bringing out fluid tar, and pouring it off from his hand as from a ladle. The tar remained in complete contact with his skin, and he wiped it off with tow. Convinced that there was no deception in this experiment, Mr. Davenport immersed the entire length of his fore-finger in the boiling cauldron, and moved it about a short time before the heat became inconvenient. Mr. Davenport ascribes this singular effect to the slowness with which the tar communicates its heat, which he conceives to arise from the abundant volatile vapour which is evolved, “carrying off rapidly the caloric in a latent state, and intervening between the tar and the skin, so as to prevent the more rapid communication of heat.” He conceives also, that when the hand is withdrawn, and the hot tar adhering to it, the rapidity with which this vapour is evolved from the surface exposed to the air cools it immediately. The workmen informed Mr. Davenport that, if a person put his hand into the cauldron with his glove on, he would be dreadfully burnt; but this extraordinary result was not put to the test of observation. But though the conjurors with fire may have availed themselves of these singular properties of individual bodies, yet the general secret of their art consisted in rendering the skin of the exposed parts callous and insensible to heat,--an effect which may be produced by continually compressing or singeing them till the skin acquires a horny consistence. A proof of this opinion is mentioned by Beckmann, who assures us, that in September, 1765, when he visited the copper-works at Awestad, one of the workmen, bribed by a little money to drink, took some of the melted copper in his hand, and, after showing it to the company, threw it against a wall. He then squeezed the fingers of his horny hand close to each other, held it a few minutes under his arm-pit, to make it perspire, as he said, and taking it again out, drew it over a ladle filled with melted copper, some of which he skimmed off, and moved his hand backwards and forwards very quickly by way of ostentation. During this performance, M. Beckmann noticed a smell like that of singed horn or leather, though the hand of the workman was not burned. This callosity of the skin may be effected by frequently moistening it with dilute sulphuric acid. Some allege that the juices of certain plants produce the same effect, while others recommend the frequent rubbing of the skin with oil. The receipt given by Albertus Magnus for this purpose was of a different nature. It consisted of a non-conducting calcareous paste, which was made to adhere to the skin by the sap of the marsh-mallow, the slimy seeds of the flea-bane, and the white of an egg. As the ancients were acquainted with the incombustibility of asbestos or amianthus, and the art of weaving it into cloth, it is highly probable that it was employed in the performance of some of their miracles, and it is equally probable that it was subsequently used, along with some of the processes already described, in enabling the victims of superstition to undergo without hazard the trial of ordeal by fire. In every country where this barbarous usage prevailed, whether in the sanctuary of the Christian idolater, or in the pagan temple of the Bramin, or under the wild orgies of the African savage, Providence seems to have provided the means of meeting it with impunity. In Catholic countries this exculpatory judgment was granted chiefly to persons in weak health, who were incapable of using arms, and particularly to monks and ecclesiastics, who could not avail themselves of the trial by single combat. The fire ordeal was conducted in the church under the inspection of the clergy: mass was at the same time celebrated, and the iron and the victims were consecrated by the sprinkling of holy water. The preparatory steps were also under the direction of the priests. It was necessary that the accused should be placed three days and three nights under their care, both before and after the trial. Under the pretence of preventing the defendant from preparing his hands by art, and in order to ascertain the result of the ordeal, his hands were covered up and sealed during the three days which preceded and followed the fiery application; and it has been plausibly conjectured by Beckmann, that during the first three days the preventive was applied to those whom they wished to acquit, and that the last three days were requisite to bring back the hands to their natural condition. In these and other cases, the accused could not have availed himself directly of the use of asbestos gloves, unless we could suppose them so made as to imitate the human skin at a distance; but the fibres of that mineral may have been imbedded in a paste which applied itself readily to all the elevations and depressions of the skin. In our own times the art of defending the hands and face, and indeed the whole body, from the action of heated iron and intense fire, has been applied to the nobler purpose of saving human life, and rescuing property from the flames. The revival and the improvement of this art we owe to the benevolence and the ingenuity of the Chevalier Aldini of Milan, who has travelled through all Europe to present this valuable gift to his species. Sir H. Davy had long ago shown that a safety lamp for illuminating mines, containing inflammable air, might be constructed of wire-gauze alone, which prevented the flame within, however large or intense, from setting fire to the inflammable air without. This valuable property, which has been long in practical use, he ascribed to the conducting and radiating power of the wire-gauze, which carried off the heat of the flame, and deprived it of its power. The Chevalier Aldini conceived the idea of applying the same material, in combination with other badly conducting substances, as a protection against fire. The incombustible pieces of dress which he uses for the body, arms, and legs, are formed out of strong cloth, which has been steeped in a solution of alum, while those for the head, hands, and feet, are made of cloth of asbestos or amianthus. The head-dress is a large cap which envelops the whole head down to the neck, having suitable perforations for the eyes, nose, and mouth. The stockings and cap are single, but the gloves are made of double amianthus cloth, to enable the fireman to take into his hand burning or red hot bodies. The piece of ancient asbestos cloth preserved in the Vatican was formed, we believe, by mixing the asbestos with other fibrous substances; but M. Aldini has executed a piece of nearly the same size, nine feet five inches long and five feet three inches wide, which is much stronger than the ancient piece, and possesses superior qualities, in consequence of having been woven without the introduction of any foreign substance. In this manufacture the fibres are prevented from breaking by the action of steam, the cloth is made loose in its fabric, and the threads are about the fiftieth of an inch in diameter. The metallic dress which is superadded to these means of defence consists of five principal pieces, viz. a _casque_ or cap, with a mask large enough to leave a proper space between it and the asbestos cap; a cuirass with its brassets; a piece of armour for the trunk and thighs; a pair of boots of double wire-gauze; and an oval shield 5 feet long by 2½ wide, made by stretching the wire-gauze over a slender frame of iron. All these pieces are made of iron wire-gauze, having the interval between its threads the twenty-fifth part of an inch. In order to prove the efficacy of this apparatus, and inspire the firemen with confidence in its protection, he showed them that a finger first enveloped in asbestos, and then in a double case of wire-gauze, might be held a long time in the flame of a spirit-lamp or candle before the heat became inconvenient. A fireman having his hand within a double asbestos glove, and its palm protected by a piece of asbestos cloth, seized with impunity a large piece of red-hot iron, carried it deliberately to the distance of 150 feet, inflamed straw with it, and brought it back again to the furnace. On other occasions the fireman handled blazing wood and burning substances, and walked during five minutes upon an iron grating placed over flaming fagots. In order to show how the head, eyes, and lungs are protected, the fireman put on the asbestos and wire-gauze cap, and the cuirass, and held the shield before his breast. A fire of shavings was then lighted, and kept burning in a large raised chafing-dish; the fireman plunged his head into the middle of the flames with his face to the fuel, and in that position went several times round the chafing-dish for a period longer than a minute. In a subsequent trial, at Paris, a fireman placed his head in the middle of a large brazier filled with flaming hay and wood, as in Fig. 77, and resisted the action of the fire during five or six minutes, and even ten minutes. [Illustration: _Fig. 77._] In the experiments which were made at Paris in the presence of a committee of the Academy of Sciences, two parallel rows of straw and brushwood, supported by iron wires, were formed at the distance of three feet from each other, and extended thirty feet in length. When this combustible mass was set on fire, it was necessary to stand at the distance of eight or ten yards to avoid the heat. The flames from both the rows seemed to fill up the whole space between them, and rose to the height of nine or ten feet. At this moment six firemen, clothed in the incombustible dresses, and marching at a slow pace behind each other, repeatedly passed through the whole length between the two rows of flame, which were constantly fed with additional combustibles. One of the firemen carried on his back a child eight years old, in a wicker-basket covered with metallic gauze, and the child had no other dress than a cap made of amianthine cloth. In February, 1829, a still more striking experiment was made in the yard of the barracks of St. Gervais. Two towers were erected two stories high, and were surrounded with heaps of inflamed materials, consisting of fagots and straw. The firemen braved the danger with impunity. In opposition to the advice of M. Aldini, one of them, with the basket and child, rushed into a narrow place, where the flames were raging eight yards high. The violence of the fire was so great that he could not be seen, while a thick black smoke spread around, throwing out a heat which was unsupportable by the spectators. The fireman remained so long invisible that serious doubts were entertained of his safety. He at length, however, issued from the fiery gulf uninjured, and proud of having succeeded in braving so great a danger. It is a remarkable result of these experiments, that the firemen are able to breathe without difficulty in the middle of the flames. This effect is owing not only to the heat being intercepted by the wire-gauze as it passes to the lungs, in consequence of which its temperature becomes supportable, but also to the singular power which the body possesses of resisting great heats, and of breathing air of high temperatures. A series of curious experiments were made on this subject by M. Tillet in France, and by Dr. Fordyce and Sir Charles Blagden in England. Sir Joseph Banks, Dr. Solander, and Sir Charles Blagden entered a room in which the air had a temperature of 198° Fahr., and remained ten minutes; but as the thermometer sank very rapidly, they resolved to enter the room singly. Dr. Solander went in alone, and found the heat 210°, and Sir Joseph entered when the heat was 211°. Though exposed to such an elevated temperature, their bodies preserved their natural degree of heat. Whenever they breathed upon a thermometer it sank several degrees: every expiration, particularly if strongly made, gave a pleasant impression of coolness to their nostrils, and their cold breath cooled their fingers whenever it reached them. On touching his side, Sir Charles Blagden found it cold like a corpse, and yet the heat of his body under his tongue was 98°. Hence they concluded that the human body possesses the power of destroying a certain degree of heat when communicated with a certain degree of quickness. This power, however, varies greatly in different media. The same person who experienced no inconvenience from air heated to 211°, could just bear rectified spirits of wine at 130°, cooling oil at 129°, cooling water at 123°, and cooling quicksilver at 117°. A familiar instance of this occurred in the heated room. All the pieces of metal there, even their watch-chains, felt so hot that they could scarcely bear to touch them for a moment, while the air from which the metal had derived all its heat was only unpleasant. Messrs. Duhamel and Tillet observed, at Rochefoucault in France, that the girls who were accustomed to attend ovens in a bakehouse were capable of enduring for ten minutes a temperature of 270°. The same gentlemen who performed the experiments above described ventured to expose themselves to still higher temperatures. Sir Charles Blagden went into a room where the heat was 1° or 2° above 260°, and remained eight minutes in this situation, frequently walking about to all the different parts of the room, but standing still most of the time in the coolest spot, where the heat was above 240°. The air, though very hot, gave no pain, and Sir Charles and all the other gentlemen were of opinion that they could support a much greater heat. During seven minutes Sir C. Blagden’s breathing continued perfectly good, but after that time he felt an oppression in his lungs, with a sense of anxiety, which induced him to leave the room. His pulse was then 144, double its ordinary quickness. In order to prove that there was no mistake respecting the degree of heat indicated by the thermometer, and that the air which they breathed was capable of producing all the well-known effects of such a heat on inanimate matter, they placed some eggs and a beef-steak upon a tin frame near the thermometer, but more distant from the furnace than from the wall of the room. In the space of twenty minutes the eggs were roasted quite hard, and in forty-seven minutes the steak was not only dressed, but almost dry. Another beef-steak, similarly placed, was rather overdone in thirty-three minutes. In the evening, when the heat was still more elevated, a third beef-steak was laid in the same place, and as they had noticed that the effect of the hot air was greatly increased by putting it in motion, they blew upon the steak with a pair of bellows, and thus hastened the dressing of it to such a degree that the greatest portion of it was found to be pretty well done in thirteen minutes. Our distinguished countryman, Sir F. Chantrey, has very recently exposed himself to a temperature still higher than any which we have mentioned. The furnace which he employs for drying his moulds is about 14 feet long, 12 feet high, and 12 feet broad. When it is raised to its highest temperature, with the doors closed, the thermometer stands at 350°, and the iron floor is red hot. The workmen often enter it at a temperature of 340°, walking over the iron floor with wooden clogs, which are of course charred on the surface. On one occasion Sir F. Chantrey, accompanied by five or six of his friends, entered the furnace, and, after remaining two minutes, they brought out a thermometer which stood at 320°. Some of the party experienced sharp pains in the tips of their ears, and in the septum of the nose, while others felt a pain in their eyes. LETTER XIII. Spontaneous combustion--In the absorption of air by powdered charcoal--and of hydrogen by spongy platinum--Dobereiner’s lamp--Spontaneous combustion in the bowels of the earth--Burning cliffs--Burning soil--Combustion without flame--Spontaneous combustion of human beings--Countess Zangari--Grace Pett--Natural fire-temples of the Guebres--Spontaneous fires in the Caspian Sea--Springs of inflammable gas near Glasgow--Natural light-house of Maracaybo--New elastic fluids in their cavities--of gems--Chemical operation going on in their cavities--Explosions produced in them by heat--Remarkable changes of colour from chemical causes--Effects of the nitrous oxide of Paradise gas when breathed--Remarkable cases described--Conclusion. Among the wonderful phenomena which chemistry presents to us, there are few more remarkable than those of spontaneous combustion, in which bodies both animate and inanimate emit flames, and are sometimes entirely consumed by internal fire. One of the commonest experiments in chemistry is that of producing inflammation by mixing two fluids perfectly cold. Becker, we believe, was the first person who discovered that this singular effect was produced by mixing oil of vitriol with oil of turpentine. Borrichios showed that aqua-fortis produced the same effect as oil of vitriol. Tournefort proved that spirit of nitre and oil of sassafras took fire when mixed; and Homberg discovered that the same property was possessed by many volatile oils when mixed with spirit of nitre. Every person is familiar with the phenomena of heat and combustion produced by fermentation. Ricks of hay and stacks of corn have been frequently consumed by the heat generated during the fermentation produced from moisture; and gunpowder-magazines, barns, and paper-mills have been often burned by the fermentation of the materials which they contained. Galen informs us that the dung of a pigeon is sufficient to set fire to a house; and he assures us that he has often seen it take fire when it had become rotten. Casati likewise relates, on good authority, that the fire which consumed the great church of Pisa was occasioned by the dung of pigeons that had for centuries built their nests under its roof. Among the substances subject to spontaneous combustion, pulverized or finely-powdered charcoal is one of the most remarkable. During the last thirty years no fewer than four cases of the spontaneous inflammation of powdered charcoal have taken place in France. When charcoal is triturated in tuns with bronze bruisers, it is reduced into the state of the finest powder. In this condition it has the appearance of an unctuous fluid, and it occupies a space three times less than it does in rods of about six inches long. In this state of extreme division it absorbs air much more readily than it does when in rods. This absorption, which is so slow as to require several days for its completion, is accompanied with a disengagement of heat which rises from 340° to 360° nearly of Fahrenheit, and which is the true cause of the spontaneous inflammation. The inflammation commences near the centre of the mass, at the depth of five or six inches beneath its surface, and at this spot the temperature is always higher than at any other. Black charcoal, strongly distilled, heats and inflames more easily than the orange, or that which is little distilled, or than the charcoal made in boilers. The most inflammable charcoal must have a mass of at least 66lbs. avoirdupois, in order that it may be susceptible of spontaneous inflammation. With the other less inflammable varieties, the inflammation takes place only in larger masses. The inflammation of powdered charcoal is more active in proportion to the shortness of the interval between its carbonization and trituration. The free admission of air to the surface of the charcoal is also indispensable to its spontaneous combustion. Colonel Aubert, to whom we owe these interesting results, likewise found that when sulphur and saltpetre are added to the charcoal, it loses its power of inflaming spontaneously. But as there is still an absorption of air and a generation of heat, he is of opinion that it would not be prudent to leave these mixtures in too large masses after trituration.[34] [34] See _Edinburgh Journal of Science_, New Series, No. viii. p. 274. A species of spontaneous combustion, perfectly analogous to that now described, but produced almost instantaneously, was discovered by Professor Dobereiner of Jena in 1824. He found that when a jet of hydrogen gas was thrown upon recently prepared spongy platinum, the metal became almost instantly red hot, and set fire to gas. In this case the minutely divided platinum acted upon the hydrogen gas in the same manner as the minutely divided charcoal acted upon common air. Heat and combustion were produced by the absorption of both gases, though in the one case the effect was instantaneous, and in the other was the result of a prolonged absorption. [Illustration: _Fig. 78._] This beautiful property of spongy platinum was happily applied to the construction of lamps for producing an instantaneous light. The form given to the lamp by Mr. Garden of London is shown in the annexed figure, where AB is a globe of glass, fitting tightly into another glass globe CD by a ground shoulder _m n_. The globe AB terminates in a hollow tapering neck _m n o p_, on the lower end of which is placed a small cylinder of zinc _o p_. A brass tube _a b c_, is fitted at _a_ into the neck of the globe CD, and through this tube, which is furnished with a stop-cock _d_, the gas can escape at the small aperture _c_. A brass pin _c f_, carrying a brass box P, is made to slide through a hole _h_, so that the brass box P, in which the spongy platinum is placed, can be set at any required distance from the aperture _c_. If sulphuric acid, diluted with an equal quantity of water, is now poured into the vessel AB by its mouth at S, now closed with a stopper, the fluid will descend through the tube _m n o p_, and if the cock _d_ is shut, it will compress the air contained in CD. The dilute acid thus introduced into CD will act upon the ring of zinc _o p_, and generate hydrogen gas, which, after the atmospheric air in CD is let off, will gradually fill the vessel CD, the diluted acid being forced up the tube _o p m n_, into the glass globe AB. The ring of zinc _o p_ floats on a piece of cork, so that when CD is full of hydrogen, the diluted acid does not touch the zinc, and consequently is prevented from producing any more gas. The instant, however, that any gas is let off at _c_, the pressure of the fluid in the globe AB, and tube _m n o p_, overcomes the elasticity of the remaining gas in CD, and forces the diluted acid up to the zinc _o p_, so as to enable it to produce more gas to supply what has been used. The lamp being supplied with hydrogen in the manner now described, it is used in the following manner. The spongy platinum in P being brought near _c_, the cock _d_ is turned, and the gas is thrown upon the platinum. An intense heat is immediately produced, the platinum becomes red-hot, and the hydrogen inflames. A taper is then lighted at the flame, and the cock _d_ is shut. Professor Cumming, of Cambridge, found it necessary to cover up the platinum with a cap after every experiment. This ingenious chemist likewise found, that, with platinum foil the 9,000th part of an inch thick kept in a close tube, the hydrogen was inflamed; but when the foil was only the 6,000th of an inch thick, it was necessary to raise it previously to a red heat. Spontaneous combustion is a phenomenon which occurs very frequently and often to a great extent within the bowels of the earth. The heat by which it is occasioned is produced by the decomposition of mineral bodies and other causes. This heat increases in intensity till it is capable of melting the solid materials which are exposed to it. Gases and aqueous vapours of powerful elasticity are generated, new fluids of expansive energy imprisoned in cavities under great pressure are set free, and these tremendous agents, acting under the repressing forces of the superincumbent strata, exhibit their power in desolating earthquakes; or, forcing their way through the superficial crust of the globe, they waste their fury in volcanic eruptions. When the phenomena of spontaneous combustion take place near the surface of the earth, its effects are of a less dangerous character, though they frequently give birth to permanent conflagrations, which no power can extinguish. An example of this milder species of spontaneous combustion has been recently exhibited in the burning cliff at Weymouth; and a still more interesting one exists at this moment near the village of Bradley, in Staffordshire. The earth is here on fire, and this fire has continued for nearly sixty years, and has resisted every attempt that has been made to extinguish it. This fire, which has reduced many acres of land to a mere calx, arises from a burning stratum of coal about four feet thick and eight or ten yards deep, to which the air has free access, in consequence of the main coal having been dug from beneath it. The surface of the ground is sometimes covered for many yards with such quantities of sulphur that it can be easily gathered. The calx has been found to be an excellent material for the roads, and the workmen who collect it often find large beds of alum of an excellent quality. A singular species of invisible combustion, or of combustion without flame, has been frequently noticed. I have observed this phenomenon in the small green wax tapers in common use. When the flame is blown out, the wick will continue red-hot for many hours; and if the taper were regularly and carefully uncoiled, and the room kept free from currents of air, the wick would burn on in this way till the whole of the taper is consumed. The same effects are not produced when the colour of the wax is red. In this experiment the wick, after the flame is blown out, has sufficient heat to convert the wax into vapour, and this vapour being consumed without flame, keeps the wick at its red heat. A very disagreeable vapour is produced during this imperfect combustion of the wax. Prof. Dobereiner, of Jena, observed that, when the alcohol in a spirit of wine lamp was nearly exhausted, the wick became carbonized, and though the flame disappeared, the carbonized part of the wick became red-hot, and continued so while a drop of alcohol remained, provided the air in the room was undisturbed. On one occasion the wick continued red-hot for twenty-four hours, and a very disagreeable acid vapour was formed. [Illustration: _Fig. 79._] On these principles depend the _lamp without flame_ which was originally constructed by Mr. Ellis. It is shown in the annexed figure, where AB is the lamp, and _h_ a cylindrical coil of platinum wire, the hundredth part of an inch in diameter. This spiral is so placed that four or five of the twelve coils of which the cylinder consists are upon the wick, and the other seven or eight above it. If the lamp is lighted, and continues burning till the cylindrical coil is red-hot, then if the flame is blown out, the vapour which arises from the alcohol will by its combustion keep the coils above the wick red-hot, and this red heat will in its turn keep up the vaporization of the alcohol till the whole of the alcohol is consumed. The heat of the wire is always sufficient to kindle a piece of German fungus or saltpetre paper, so that a sulphur match may at any time be lighted. Mr. Gill found that a wick composed of twelve threads of the cotton yarn commonly used for lamps will require half an ounce of alcohol to keep the wire red-hot for eight hours. This lamp has been kept burning for sixty hours; but it can scarcely be recommended for a bed-room, as an acid vapour is disengaged during the burning of the alcohol. When perfumes are dissolved in the alcohol, they are diffused through the apartment during the slow combustion of the vapour. A species of combustion without flame, and analogous to that which has been described, is exhibited in the extraordinary phenomenon of the spontaneous combustion of living bodies. That animal bodies are liable to internal combustion, is a fact which was well known to the ancients. Many cases which have been adduced as examples of spontaneous combustion are merely cases of individuals who were highly susceptible of strong electrical excitation. In one of these cases, however, Peter Bovisteau asserts, that the sparks of fire thus produced, reduced to ashes the hair of a young man; and John de Viana informs us, that the wife of Dr. Freilas, physician to the Cardinal de Royas, Archbishop of Toledo, emitted by perspiration an inflammable matter of such a nature, that when the ribbon which she wore over her shift was taken from her, and exposed to the cold air, it instantly took fire, and shot forth like grains of gunpowder. Peter Borelli has recorded a fact of the very same kind respecting a peasant whose linen took fire, whether it was laid up in a box when wet, or hung up in the open air. The same author speaks of a woman who, when at the point of death, vomited flames; and Thomas Bartholin mentions this phenomenon as having often happened to persons who were great drinkers of wine or brandy. Ezekiel de Castro mentions the singular case of Alexandrinus Megetius, a physician, from one of whose vertebræ there issued a fire which scorched the eyes of the beholders; and Krantzius relates, that during the wars of Godfrey of Bouillon, certain people of the territory of Nevers were burning with invisible fire, and that some of them cut off a foot or a hand where the burning began, in order to arrest the calamity. Nor have these effects been confined to man. In the time of the Roman consuls Gracchus and Juventius, a flame is said to have issued from the mouth of a bull without doing any injury to the animal. The reader will judge of the degree of credit which may belong to these narrations when he examines the effects of a similar kind which have taken place in less fabulous ages, and nearer our own times. John Henry Cohausen informs us that a Polish gentleman in the time of the Queen Bona Sforza, having drunk two dishes of a liquor called brandy-wine, vomited flames, and was burned by them, and Thomas Bartholin[35] thus describes a similar accident: “A poor woman at Paris used to drink spirit of wine plentifully for the space of three years, so as to take nothing else. Her body contracted such a combustible disposition, that one night, when she lay down on a straw couch, she was all burned to ashes except her skull and the extremities of her fingers.” John Christ. Sturmius informs us, in the German Ephemerides, that in the northern countries of Europe flames often evaporate from the stomachs of those who are addicted to the drinking of strong liquors; and he adds, “that seventeen years before, three noblemen of Courland drank by emulation strong liquors, and two of them died scorched and suffocated by a flame which issued from their stomachs.” [35] Acta Medica et Philosophica Hafniensia, 1673. One of the most remarkable cases of spontaneous combustion is that of the Countess Cornelia Zangari and Bandi of Cesena, which has been minutely described by the Reverend Joseph Bianchini, a prebend in the city of Verona. This lady, who is in the sixty-second year of her age, retired to bed in her usual health. Here she spent above three hours in familiar conversation with her maid, and in saying her prayers; and having at last fallen asleep, the door of her chamber was shut. As her maid was not summoned at the usual hour, she went into the bed-room to wake her mistress; but receiving no answer, she opened the window, and saw her corpse on the floor in the most dreadful condition. At the distance of four feet from the bed there was a heap of ashes. Her legs, with the stockings on, remained untouched, and the head, half burned, lay between them. Nearly all the rest of the body was reduced to ashes. The air in the room was charged with floating soot. A small oil lamp on the floor was covered with ashes, but had no oil in it; and in two candlesticks, which stood upright upon a table, the cotton wick of both the candles was left, and the tallow of both had disappeared. The bed was not injured, and the blankets and sheets were raised on one side, as if a person had risen up from it. From an examination of all the circumstances of this case, it has been generally supposed that an internal combustion had taken place; that the lady had risen from her bed to cool herself, and that, in her way to open the window, the combustion had overpowered her, and consumed her body by a process in which no flame was produced which could set fire to the furniture or the floor. The Marquis Scipio Maffei was informed by an Italian nobleman who passed through Cesena a few days after this event, that he heard it stated in that town, that the Countess Zangari was in the habit, when she felt indisposed, of washing all her body with camphorated spirit of wine. So recently as 1744, a similar example of spontaneous combustion occurred in our own country, at Ipswich. A fisherman’s wife, of the name of Grace Pett, of the parish of St. Clement’s, had been in the habit for several years of going down stairs every night, after she was half undressed, to smoke a pipe. She did this on the evening of the 9th of April, 1744. Her daughter, who lay in the same bed with her, had fallen asleep, and did not miss her mother till she awaked early in the morning. Upon dressing herself, and going down stairs, she found her mother’s body lying on the right side, with her head against the grate, and extended over the hearth, with her legs on the deal floor, and appearing like a block of wood burning with a glowing fire without flame. Upon quenching the fire with two bowls of water, the neighbours, whom the cries of the daughter had brought in, were almost stifled with the smell. The trunk of the unfortunate woman was almost burned to ashes, and appeared like a heap of charcoal covered with white ashes. The head, arms, legs, and thighs, were also much burned. There was no fire whatever in the grate, and the candle was burned out in the socket of the candlestick, which stood by her. The clothes of a child on one side of her, and a paper screen on the other, were untouched: and the deal floor was neither singed nor discoloured. It was said that the woman had drunk plentifully of gin overnight in welcoming a daughter who had recently returned from Gibraltar. Among the phenomena of the natural world which are related to those of spontaneous combustion, are what have been called the natural fire-temples of the Guebres, and the igneous phenomena which are seen in their vicinity. The ancient sect of the Guebres or Parsees, distinguished from all other sects as the worshippers of fire, had their origin in Persia; but, being scattered by persecution, they sought an asylum on the shores of India. Those who refused to expatriate themselves continued to inhabit the shores of the Caspian Sea, and the cities of Ispahan, Yezd, and Kerman. Their great fire-temple, called Attush Kudda, stands in the vicinity of Badku, one of the largest and most commodious ports on the Caspian. In the neighbourhood of this town the earth is impregnated with naphtha, an inflammable mineral oil; and the inhabitants have no other fuel, and no other light, but what is derived from this substance. The remains of the ancient fire-temples of the Guebres are still visible about ten miles to the north-east of the town. The temple in which the deity is worshipped under the form of fire, is a space about thirty yards square, surrounded with a low wall, and containing many apartments. In each of these a small volcano of sulphureous fire issues from the ground through a furnace or funnel in the shape of a Hindoo altar. On closing the funnel, the fire is instantly extinguished; and by placing the ear at the aperture, a hollow sound is heard, accompanied with a strong current of cold air, which may be lighted at pleasure by holding to it any burning substance. The flame is of a pale, clear colour, without any perceptible smoke, and emits a highly sulphureous vapour, which impedes respiration, unless when the mouth is kept beneath the level of the furnace. This action on the lungs gives the Guebres a wan and emaciated appearance, and oppresses them with a hectic cough, which strangers also feel while breathing this insalubrious atmosphere. For about two miles in circumference, round the principal fire, the whole ground, when scraped to the depth of two or three inches, has the singular property of being inflamed by a burning coal. In this case, however, it does not communicate fire to the adjacent ground: but if the earth is dug up with a spade, and a torch brought near it, an extensive but instantaneous conflagration takes place, in which houses have often been destroyed, and the lives of the people exposed to imminent danger. When the sky is clear and the weather serene, the springs in their ebullition do not rise higher than two or three feet; but in gloomy weather, and during the prevalence of stormy clouds, the springs are in a state of the greatest ebullition, and the naphtha, which often takes fire spontaneously at the earth’s surface, flows burning in great quantities to the sea, which is frequently covered with it, in a state of flame, to the distance of several leagues from the shore. Besides the fires in the temple, there is a large one which springs from a natural cliff in an open situation, and which continually burns. The general space in which this volcanic fire is most abundant is somewhat less than a mile in circuit. It forms a low flat hill, sloping to the sea, the soil of which is a sandy earth, mixed with stones. Mr. Forster did not observe any violent eruption of flame in the country around the Attush Kudda; but Kinneir informs us, that the whole country round Badku has at times the appearance of being enveloped in flames. “It often seems,” he adds, “as if the fire rolled down from the mountains in large masses, and with incredible velocity; and during the clear moonshine nights of November and December, a bright blue light is observed at times to cover the whole western range. The fire does not consume; and if a person finds himself in the middle of it, no warmth is felt.” The inhabitants apply these natural fires to domestic purposes, by sinking a hollow cane or merely a tube of paper, about two inches in the ground, and by blowing upon a burning coal held near the orifice of the tube, there issues a slight flame, which neither burns the cane nor the paper. By means of these canes or paper tubes, from which the fire issues, the inhabitants boil the water in their coffee-urns, and even cook different articles of food. The flame is put out by merely plugging up the orifice. The same tubes are employed for illuminating houses that are not paved. The smell of naphtha is of course diffused through the house: but after any person is accustomed to it, it ceases to be disagreeable. The inhabitants also employ this natural fire in calcining lime. The quantity of naphtha procured in the plain to the south-east of Badku is enormous. It is drawn from wells, some of which yield from 1,000 to 1,500lbs. per day. As soon as these wells are emptied, they fill again till the naphtha rises to its original level.[36] [36] See Forster’s Travels, and Kinneir’s Geog. Memoir. Inflammable gases issuing from the earth have been used both in the old and the new world for domestic purposes. In the salt mine of Gottesgabe, at Rheims, in the county of Fecklenburg, there is a pit called the _Pit of the Wind_, from which a constant current of inflammable gas has issued for sixty years. M. Roeder, the inspector of the mines, has used this gas for two years, not only as a light, but for all the purposes of domestic economy. In the pits which are not worked, he collects the gas, and conveys it in tubes to his house. It burns with a white and brilliant flame, has a density of about O.66, and contains traces of carbonic acid gas and sulphuretted hydrogen.[37] [37] _Edinburgh Journal of Science_, No. xv., p. 183. Near the village of Fredonia, in North America, on the shores of Lake Erie, are a number of burning springs, as they are called. The inflammable gas which issues from these springs is conveyed in pipes to the village, which is actually lighted by them.[38] [38] _Edinburgh Journal of Science_, No. xv., p. 183. In the year 1828 a copious spring of inflammable gas was discovered in Scotland, in the bed of a rivulet which crosses the north road between Glasgow and Edinburgh, a little to the east of the seventh mile-stone from Glasgow, and only a few hundred yards from the house of Bedlay. The gas is said to issue for more than half a mile along the banks of the rivulet. Dr. Thompson, who has analysed the gas, saw it issuing only within a space about fifty yards in length, and about half as much in breadth. “The emission of gas was visible in a good many places along the declivity to the rivulet in the immediate neighbourhood of a small farm-house. The farmer had set the gas on fire in one place about a yard square, out of which a great many small jets were issuing. It had burnt without interruption during five weeks, and the soil (which was clay) had assumed the appearance of pounded brick all around. “The flame was yellow and strong, and resembled perfectly the appearance which _carburetted hydrogen gas_ or _fire-damp_ presents when burnt in daylight. But the greatest issue of gas was in the rivulet itself, distant about twenty yards from the place where the gas was burning. The rivulet, when I visited the place, was swollen and muddy, so as to prevent its bottom from being seen. But the gas issued up through it in one place with great violence, as if it had been in a state of compression under the surface of the earth; and the thickness of the jet could not be less than two or three inches in diameter. We set the gas on fire as it issued through the water. It burnt for some time with a good deal of splendour; but as the rivulet was swollen, and rushing along with great impetuosity, the regularity of the issue was necessarily disturbed, and the gas was extinguished.” Dr. Thompson found this gas to consist of _two_ volumes of hydrogen gas, and _one_ volume of vapour of carbon; and as its specific gravity was 0.555, and as it issues in great abundance, he remarks that it might be used for filling air-balloons. “Were we assured,” he adds, “that it would continue to issue in as great abundance as at present, it might be employed in lighting the streets of Glasgow.”[39] [39] _Edinburgh Journal of Science_, No. 1, New Series, p. 71-75. A very curious natural phenomenon, called the _Lantern_ or _Natural Lighthouse_ of Maracaybo, has been witnessed in South America. A bright light is seen every night on a mountainous and uninhabited spot on the banks of the river Catatumbo, near its junction with the Sulia. It is easily distinguished at a greater distance than _forty_ leagues, and as it is nearly in the meridian of the opening of the Lake of Maracaybo, navigators are guided by it as by a light-house. This phenomenon is not only seen from the sea-coast, but also from the interior of the country--at Merida, for example, where M. Palacios observed it for two years. Some persons have ascribed this remarkable phenomenon to a thunder-storm, or to electrical explosions which might take place daily in a pass in the mountains; and it has even been asserted, that the rolling of thunder is heard by those who approach the spot. Others suppose it to be an air-volcano, like those on the Caspian Sea, and that it is caused by asphaltic soils like those of Mena. It is more probable, however, that it is a sort of carburetted hydrogen, as hydrogen gas is disengaged from the ground in the same district.[40] [40] Humboldt’s Personal Narrative, vol. iv. p. 254, note. Grand as the chemical operations are which are going on in the great laboratory of Nature, and alarming as their effects appear when they are displayed in the terrors of the earthquake and the volcano, yet they are not more wonderful to the philosopher than the minute though analogous operations which are often at work near our own persons, unseen and unheeded. It is not merely in the bowels of the earth that highly expansive elements are imprisoned and restrained, and occasionally called into tremendous action by the excitation of heat and other causes. Fluids and vapours of a similar character exist in the very gems and precious stones which science has contributed to luxury and to the arts. In examining with the microscope the structure of mineral bodies, I discovered in the interior of many of the gems thousands of cavities of various forms and sizes. Some had the shape of hollow and regularly formed crystals; others possessed the most irregular outline, and consisted of many cavities and branches united without order, but all communicating with each other. These cavities sometimes occurred singly, but most frequently in groups forming strata of cavities, at one time perfectly flat and at another time curved. Several such strata were often found in the same specimen, sometimes parallel to each other, at other times inclined, and forming all varieties of angles with the faces of the original crystal. These cavities, which occurred in _sapphire_, _chrysoberyl_, _topaz_, _beryl_, _quartz_, _amethyst_, _peridot_, and other substances, were sometimes sufficiently large to be distinctly seen by the naked eye, but most frequently they were so small as to require a high magnifying power to be well seen, and often they were so exceedingly minute, that the highest magnifying powers were unable to exhibit their outline. [Illustration: _Fig. 80._] The greater number of these cavities, whether large or small, contained two new fluids different from any hitherto known, and possessing remarkable physical properties. These two fluids are in general perfectly transparent and colourless, and they exist in the same cavity in actual contact, without mixing together in the slightest degree. One of them expands _thirty_ times more than water, and at a temperature of about 80° of Fahrenheit it expands so as to fill up the vacuity in the cavity. This will be understood from the annexed figure, where A B C D is the cavity, _m n p o_ the highly expansible fluid in which at low temperatures there is always a vacuity V, like an air-bubble in common fluids, and A _m n_, C _o p_, the second fluid occupying the angles A and C. When heat such as that of the hand is applied to the specimen, the vacuity V gradually contracts in size, and wholly vanishes at a temperature of about 80°, as shown in Fig. 81. The fluids are shaded, as in these two figures, when they are seen by light reflected from their surfaces. [Illustration: _Fig. 81._] [Illustration: _Fig. 82._] When the cavities are large, as in Fig. 82, compared with the quantity of expansible fluid _m n p o_, the heat converts the fluid into vapour, an effect which is shown by the circular cavity V becoming larger and larger till it fills the whole space _m n o p_. When any of these cavities, whether they are filled with fluid or with vapour, is allowed to cool, the vacuity V reappears at a certain temperature. In the fluid cavities the fluid contracts, and the small vacuity appears, which grows larger and larger till it resumes its original size. When the cavities are large, several small vacuities make their appearance and gradually unite into one, though they sometimes remain separate. In deep cavities a very remarkable phenomenon accompanies the reappearance of the vacuity. At the instant that the fluid has acquired the temperature at which it quits the sides of the cavity, an effervescence or rapid ebullition takes place, and the transparent cavity is for a moment opaque, with an infinite number of minute vacuities, which instantly unite into one that goes on enlarging as the temperature diminishes. In the vapour cavities the vapour is reconverted by the cold into fluid, and the vacuity V, Fig. 82, gradually contracts till all the vapour has been precipitated. It is curious to observe, when a great number of cavities are seen at once in the field of the microscope, that the vacuities all disappear and reappear at the same instant. While all these changes are going on in the expansive fluid, the other denser fluid at A and C, Fig. 80, 81, remains unchanged either in its form or magnitude. On this account I experienced considerable difficulty in proving that it was a fluid. The improbability of two fluids existing in a transparent state in absolute contact, without mixing in the slightest degree, or acting upon each other, induced many persons to whom I showed the phenomenon to consider the lines _m n_, _o p_, Fig. 80, 81, as a partition in the cavity, or the spaces A _m n_, _o p_ C, either as filled with solid matter, or as corners into which the expanding fluid would not penetrate. The regular curvature, however, of the boundary line _m n_, _o p_, and other facts, rendered these suppositions untenable. [Illustration: _Fig. 83._] This difficulty was at last entirely removed by the discovery of a cavity of the form shown in the annexed figure, where A, B, and C are three portions of the expansible fluid separated by the interposition of the second fluid D E F. The first portion A of the expansible fluid had four vacuities V, X, Y, Z, while the other two portions B, C, had no vacuity. In order to determine if the vacuities of the portions B, C, had passed over to A, I took an accurate drawing of the appearances at a temperature of 50°, as shown in the figure, and I watched the changes which took place in raising the temperature to 83°. The portion A gradually expanded itself till it filled up all the four vacuities V, X, Y, and Z, but as the portions B, C, had no vacuities, they could expand themselves only by pushing back the supposed second fluid D E F. This effect actually took place. The dense fluid quitted the side of the cavity at F. The two portions B, C, of the expansible fluid instantly united, and the dense fluid having retreated to the limit _m_ _n_ _o_, its other limit advanced to _p_ _q_ _r_, thus proving it to be a real fluid. This experiment, which I have often shown to others, involves one of those rare combinations of circumstances which nature sometimes presents to us in order to illustrate her most mysterious operations. Had the portions B, C, been accompanied, as is usual, with their vacuities, the interposed fluid would have remained immoveable between the two equal and opposite expansions; but owing to the accidental circumstance of these vacuities having passed over into the other branch A of the cavity, the fluid yielded to the difference of the expansive forces between which it lay, and thus exhibited its fluid character to the eye. [Illustration: _Fig. 84._] When we examine these cavities narrowly, we find that they are actually little laboratories, in which chemical operations are constantly going on, and beautiful optical phenomena continually displaying themselves. Let A B D C, for example, be the summit of a crystallized cavity in topaz, S S representing the dense, N N the expansible fluid, bounded by a circular line _a b c d_, and V V the vacuity in the new fluid, bounded by the circle _e f g h_. If the face A B D C is placed under a compound microscope, so that light may be reflected at an angle less than that of total reflexion, and if the observer now looks through the microscope, the temperature of the room being 50°, he will see the second fluid S S shining with a very feeble reflected light, the dense fluid N N with a light perceptibly brighter, and the vacuity V V with a light of considerable brilliancy. The boundaries _a b c d_, _e f g h_, are marked by a well-defined outline, and also by the concentric coloured rings of thin plates produced by the extreme thinness of each of the fluids at their edges. If the temperature of the room is raised slowly to 58°, a brown spot will appear at _x_ in the centre of the vacuity V V. This spot indicates the commencement of evaporation from the expansible fluid below, and arises from the partial precipitation of the vapour in the roof of the cavity. As the heat increases, the brown spot enlarges and becomes very dark. It is then succeeded by a white spot and one or more coloured rings rise in the centre of the vacuity. The vapour then seems to form a drop, and all the rings disappear by retiring to the centre, but only to reappear with new lustre. During the application of heat, the circle _e f g h_ contracts and dilates like the pupil of the eye. When the vaporization is so feeble as to produce only a single ring of one or two tints of the second order, they vanish instantly by breathing upon the crystal; but when the slight heat of the breath reaches the fluid, it throws off fresh vapour, and the rings again appear. If a drop of ether is put upon the crystal when the rings are in a state of rapid play, the cold produced by its evaporation causes them to disappear, till the temperature again rises. When the temperature is perfectly uniform, the rings are stationary, as shown between V and V in fig. 84; and it is interesting to observe the first ring produced by the vapour swelling out to meet the first ring at the margin of the fluid, and sometimes coming so near it that the darkest parts of both form a broad black band. As the heat increases, the vacuity V V diminishes and disappears at 79°, exhibiting many curious phenomena, which we have not room to describe. Having fallen upon a method of opening the cavities, and looking at the fluids, I was able to examine their properties with more attention. When the expansible fluid first rises from the cavity upon the surface of the topaz, it neither remains still like the fixed oils, nor disappears like evaporable fluids. Under the influence, no doubt, of heat and moisture, it is in a state of constant motion, now spreading itself on a thin plate over a large surface, and now contracting itself into a deeper and much less extended drop. These contractions and extensions are marked by very beautiful optical phenomena. When the fluid has stretched itself out into a thin plate, it ceases to reflect light like the thinnest part of the soap-bubble; and when it is again accumulated into a thicker drop, it is covered with thin coloured rings of thin plates. After performing these motions, which sometimes last for ten minutes, the fluid suddenly disappears, and leaves behind it a sort of granular residue. When examining this with a single microscope, it again started into a fluid state, and extended and contracted itself as before. This was owing to the humidity of the hand which held the microscope, and I have been able to restore by moisture the fluidity of these grains twenty days after they were formed from the fluid. This portion was shown to the Rev. Dr. Fleming, who remarked, that, had he observed it accidentally, he would have ascribed its apparent vitality to the movements of some of the animals of the genus Planaria. After the cavity has remained open for a day or two, the dense fluid comes out and quickly hardens into a transparent and yellowish resinous-looking substance, which absorbs moisture, though with less avidity than the other. It is not volatilized by heat, and is insoluble in water and alcohol. It readily dissolves, however, with effervescence in the sulphuric, nitric, and muriatic acids. The residue of the expansible fluid is volatilized by heat, and is dissolved, but without effervescence, in the above-mentioned acids. The refractive power of the dense fluid is about 1.295, and of the expansible one 1.131. The particles of the dense fluid have a very powerful attraction for each other and for the mineral which contains them, while those of the expansible fluid have a very slight attraction for one another, and also for the substance of the mineral. Hence the two fluids never mix, the dense fluid being attracted to the angles of angular cavities, or filling the narrow necks by which two cavities communicate. The expansible fluid, on the other hand, fills the wide parts of the cavities, and in deep and round cavities it lies above the dense fluid. When the dense fluid occupies the necks which join two cavities, it performs the singular function of a fluid valve, opening and shutting itself according to the expansions or contractions of the other fluid. The _fluid valves_ thus exhibited in action may suggest some useful hints to the mechanic and the philosopher, while they afford ground of curious speculation in reference to the functions of animal and vegetable bodies. In the larger organizations of ordinary animals, where gravity must in general overpower, or at least modify, the influence of capillary attraction, such a mechanism is neither necessary nor appropriate; but, in the lesser functions of the same animals, and in almost all the microscopic structures of the lower world, where the force of gravity is entirely subjected to the more powerful energy of capillary forces, it is extremely probable that the mechanism of immiscible fluids and fluid valves is generally adopted. In several cavities in minerals I have found crystallized and other bodies, sometimes transparent crystals, sometimes black spicular crystals, and sometimes black spheres, all of which are moveable within the cavity. In some cavities the two new fluids occur in an indurated state, and others I have found to be lined with a powdery matter. This last class of cavities occurred in topaz, and they were distinguished from all others by the extraordinary beauty and symmetry of their form. One of these cavities represented a finely ornamented sceptre, and, what is still more singular, the different parts of which it is composed lay in different planes. When the gem which contains the highly expansive fluid is strong, and the cavity not near the surface, heat may be applied to it without danger; but in the course of my experiments on this subject, the mineral has often burst with a tremendous explosion, and in one case wounded me on the brow. An accident of the same kind occurred to a gentleman who put a crystal into his mouth for the purpose of expanding the fluid. The specimen burst with great force and cut his mouth, and the fluid which was discharged from the cavity had a very disagreeable taste. In the gems which are peculiarly appropriated for female ornaments, cavities containing the expansive fluid frequently occur, and if these cavities should happen to be very near the surface or the edge of the stone, the fever heat of the body might be sufficient to burst them with an alarming and even dangerous explosion. I have never heard of any such accident having occurred; but if it has, or if it ever shall occur, and if its naturally marvellous character shall be heightened by any calamitous results, the phenomena described in the preceding pages will strip it of its wonder. There are no facts in chemistry more interesting than those which relate to the changes of colour, which are produced by the mixture of fluids, and to the creation of brilliant colours by the combination of bodies in which no colouring matter is visible. Facts of this kind are too common and too generally known to require to be noticed in a work like this. The art of producing such changes was known to some of the early impostors, who endeavoured to obtain a miraculous sanction to their particular dogmas. Marcos, the head of one of the sects that wished to engraft paganism upon Christianity, is said to have filled three transparent glasses with white wine, and while he prayed, the wine in one of the glasses became red like blood, that in another became purple, and that in the third sky-blue. Such transformations present no difficulty to the chemist. There are several fluids, such as some of the coloured juices of plants, which change their colour rapidly and without any additional ingredient: and in other cases, there would be no difficulty in making additions to fluids which should produce a change of colour at any required instant. A very remarkable experiment of an analogous nature has been publicly exhibited in modern times. Professor Beyruss, who lived at the court of the Duke of Brunswick, one day pronounced to his highness that the dress which he wore should during dinner became red; and the change actually took place, to the astonishment of the prince and the rest of his guests. M. Vogel, who has recorded this curious fact, has not divulged the secret of the German chemist; but he observes, that if we pour lime-water into the juice of beet-root, we shall obtain a colourless liquid; and that a piece of white cloth dipped in this liquid and dried rapidly, will in a few hours become red by the mere contact of air. M. Vogel is also of opinion that this singular effect would be accelerated in an apartment where champagne or other fluids charged with carbonic acid are poured out in abundance. Among the wonders of chemistry we must number the remarkable effects produced upon the human frame by the inhalation of _paradise_ or _intoxicating gas_, as it has been called. This gas is known to chemists by the name of the _nitrous oxide_, or the _gaseous oxide of azote_, or the _protoxide of nitrogen_. It differs from atmospheric air only in the proportion of its ingredients, atmospheric air being composed of twenty-seven parts of oxygen, and seventy-three of nitrogen, while the nitrous oxide consists of thirty-seven parts of oxygen, and sixty-seven of nitrogen. The most convenient way of procuring the gas is to expose nitrate of ammonia in a tubulated glass retort to the heat of an Argand’s lamp between 400° and 500° of Fahrenheit. The salt first melts; bubbles of gas begin to rise from the mass, and in a short time a brisk effervescence takes place, which continues till all the salt has disappeared. The products of this operation are the nitrous oxide and water, the watery vapour being condensed in the neck of the retort, while the gas is received over water. The gas thus obtained is generally white, and hence, when it is to be used for the purposes of respiration, it should remain at least an hour over water, which will absorb the small quantity of acid and of nitrate of ammonia which adhere to it. A pound of the nitrate of ammonia will in this way yield five cubic feet of gas fit for the purpose of inhalation. It was discovered by Sir Humphrey Davy, that this gas could be safely taken into the lungs, and that it was capable of supporting respiration for a few minutes. In making this experiment he was surprised to find that it produced a singular species of intoxication, which he thus describes: “I breathed,” says he, “three quarts of oxide from and into a silk bag for more than half a minute without previously closing my nose or exhausting my lungs. The first inspiration caused a slight degree of giddiness. This was succeeded by an uncommon sense of fulness in the head, accompanied with loss of distinct sensation and voluntary power, a feeling analogous to that produced in the first stage of intoxication, but unattended by pleasurable sensations.” In describing the effects of another experiment, he says, “Having previously closed my nostrils and exhausted my lungs, I breathed four quarts of nitrous oxide from and into a silk bag. The first feelings were similar to those produced in the last experiment, but in less than half a minute, the respiration being continued, they diminished gradually, and were succeeded by a highly pleasurable thrilling, particularly in the chest and the extremities. The objects around me became dazzling, and my hearing more acute. Towards the last respiration the thrilling increased, the sense of muscular power became greater, and at last an irresistible propensity to action was indulged in. I recollect but indistinctly what followed; I knew that my motions were varied and violent. These effects very rarely ceased after respiration. In ten minutes I had recovered my natural state of mind. The thrilling in the extremities continued longer than the other sensations. This experiment was made in the morning; no languor or exhaustion was consequent, my feelings through the day were as usual, and I passed the night in undisturbed repose.” In giving an account of another experiment with this gas, Sir Humphrey thus describes his feelings: “Immediately after my return from a long journey, being fatigued, I respired nine quarts of nitrous oxide, having been precisely thirty-three days without breathing any. The feelings were different from those I had experienced on former experiments. After the first six or seven respirations, I gradually began to lose the perception of external things, and a vivid and intense recollection of some former experiments passed through my mind, so that I called out, ‘What an annoying concatenation of ideas!’” Another experiment made by the same distinguished chemist was attended by still more remarkable results. He was shut up in an airtight breathing-box, having a capacity of about nine and a half cubic feet, and he allowed himself to be habituated to the excitement of the gas, which was gradually introduced. After having undergone this operation for an hour and a quarter, during which eighty quarts of gas were thrown in, he came out of the box and began to respire twenty quarts of unmingled nitrous oxide. “A thrilling,” says he, “extending from the chest to the extremities, was almost immediately produced. I felt a sense of tangible extension highly pleasurable in every kind; my visible impressions were dazzling and apparently magnified; I heard distinctly every sound in the room, and I was perfectly aware of my situation. By degrees, as the pleasurable sensation increased, I lost all connexion with external things; trains of vivid visible images rapidly passed through my mind, and were connected with words in such a manner as to produce perceptions perfectly novel. I existed in a world of newly connected and newly modified ideas. When I was awakened from this same delirious trance by Dr. Kinglake, who took the bag from my mouth, indignation and pride were the first feelings produced by the sight of the persons about me. My emotions were enthusiastic and sublime, and for a moment I walked round the room, perfectly regardless of what was said to me. As I recovered my former state of mind, I felt an inclination to communicate the discoveries I had made during the experiment. I endeavoured to recall the ideas; they were feeble and indistinct. One recollection of terms, however, presented itself, and with the most intense belief and prophetic manner I exclaimed to Dr. Kinglake, ‘Nothing exists but thoughts; the universe is composed of impressions, ideas, pleasures, and pains!’” These remarkable properties induced several persons to repeat the experiment of breathing this exhilarating medicine. Its effects were, as might have been expected, various in different individuals; but its general effect was to produce in the gravest and most phlegmatic the highest degree of exhilaration and happiness unaccompanied with languor or depression. In some it created an irresistible disposition to laugh, and in others a propensity to muscular exertion. In some it impaired the intellectual functions, and in several it had no sensible effect, even when it was breathed in the purest state, and in considerable quantities. It would be an inquiry of no slight interest to ascertain the influence of this gas over persons of various bodily temperaments, and upon minds varying in their intellectual and moral character. Although Sir Humphrey Davy experienced no unpleasant effects from the inhalation of the nitrous oxide, yet such effects are undoubtedly produced; and there is reason to believe that even permanent changes in the constitution may be induced by the operation of this remarkable stimulant. Two very interesting cases of this kind presented themselves to Professor Silliman, of Yale College, when the nitrous oxide was administered to some of his pupils. The students had been in the habit, for several years, of preparing this gas, and administering it to one another, and these two cases were the only remarkable ones which deserved to be recorded. We shall describe them in Professor Silliman’s own words:-- “A gentleman, about nineteen years of age, of a sanguine temperament, and cheerful temper, and in the most perfect health, inhaled the usual quantity of the nitrous oxide, when prepared in the ordinary manner. Immediately his feelings were uncommonly elevated, so that, as he expressed it, he could not refrain from dancing and shouting. Indeed to such a degree was he excited, that he was thrown into a frightful fit of delirium, and his exertions became so violent, that after a while he sank to the earth exhausted, and there remained, until having by quiet in some degree recovered his strength, he again arose, only to renew the most convulsive muscular efforts, and the most piercing screams and cries; within a few moments, overpowered by the intensity of the paroxysm, he again fell to the ground, apparently senseless, and panting vehemently. The long continuance and violence of the affection alarmed his companions, and they ran for professional assistance. They were, however, encouraged by the person to whom they applied to hope that he would come out of his trance without injury; but for the space of two hours these symptoms continued; he was perfectly unconscious of what he was doing, and was in every respect like a maniac. He states, however, that his _feelings vibrated_ between perfect happiness and the most consummate misery. In the course of the afternoon, and after the first violent effects had subsided, he was compelled to lie down two or three times from excessive fatigue, although he was immediately aroused upon any one’s entering the room. The effects remained in a degree for three or four days, accompanied by a hoarseness, which he attributed to the exertion made while under the immediate influence of the gas. This case should produce a degree of caution, especially in persons of a sanguine temperament, whom, much more frequently than others, we have seen painfully, and even alarmingly affected.” The other case described by Professor Silliman was that of a man of mature age, and of a grave and respectable character. “For nearly two years previous to his taking the gas, his health had been very delicate, and his mind frequently gloomy and depressed. This was peculiarly the case for a few days immediately preceding that time; and his general state of health was such, that he was obliged almost entirely to discontinue his studies, and was about to have recourse to medical assistance. In this state of bodily and mental debility, he inspired about three quarts of nitrous oxide. The consequences were, an astonishing invigoration of his whole system, and the most exquisite perceptions of delight. These were manifested by an uncommon disposition for pleasantry and mirth, and by extraordinary muscular power. The effects of the gas were felt without diminution for at least thirty hours, and in a greater or less degree for more than a week. “But the most remarkable effect was that _upon the organs of taste_. Antecedently to taking the gas, he exhibited no peculiar choice in the articles of food, but immediately subsequent to that event, he _manifested a taste for such things only as were sweet_, and for several days _ate nothing but sweet cake_. Indeed this singular taste was carried to such excess, that he used _sugar and molasses, not only upon his bread and butter, and lighter food, but upon his meat and vegetables_. This he continues to do even at the present time; and although eight weeks have elapsed since he inspired the gas, he is still found _pouring molasses over beef, fish, poultry, potatoes, cabbage, or whatever animal or vegetable food is placed before him_. “His health and spirits since that time have been uniformly good, and he attributes the restoration of his strength and mental energy to the influence of the nitrous oxide. He is entirely regular in his mind, and now experiences no uncommon exhilaration, but is habitually cheerful, while before he was as habitually grave, and even to a degree gloomy.” * * * * * Such is a brief and general account of the principal phenomena of Nature, and the most remarkable deductions of science, to which the name of Natural Magic has been applied. If those who have not hitherto sought for instruction and amusement in the study of the material world, shall have found a portion of either in the preceding pages, they will not fail to extend their inquiries to other popular departments of science, even if they are less marked with the attributes of the marvellous. In every region of space, from the infinitely distant recesses of the heavens to the “dark unfathomed caves of ocean,” the Almighty has erected monuments of miraculous grandeur, which proclaim the power, the wisdom, and the beneficence of their Author. The inscriptions which they bear--the hand-writing which shines upon their walls--appeal to the understanding and to the affections, and demand the admiration and the gratitude of every rational being. To remain willingly ignorant of these revelations of the Divine Power is a crime next to that of rejecting the revelation of the Divine Will. Knowledge, indeed, is at once the handmaid and the companion of true religion. They mutually adorn and support each other; and beyond the immediate circle of our secular duties, they are the only objects of rational ambition. While the calm deductions of reason regulate the ardour of Christian zeal, the warmth of a holy enthusiasm gives a fixed brightness to the glimmering lights of knowledge. It is one of the darkest spots in the history of man, that these noble gifts have been so seldom combined. In the young mind alone can the two kindred seeds be effectually sown; and among the improvements which some of our public institutions require, we yet hope to witness a national system of instruction, in which the volumes of Nature and of Revelation shall be simultaneously perused.