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can resist their force; and the agitation of the air, which they produce is so violent that every obstacle to their progress is overturned. In the neighbourhood of Baréges whole villages have sometimes been thus overwhelmed. No country is richer in natural productions than that of the Pyrenees; the geologist may find here numberless beauties, and ever fresh sources of instruction; the mineralogist a multitude of the most cnrious minerals; the botanist, passing in the same day from the greatest heat to the most intense cold, meets in his way every species of plants, from those which grow in the Alps and in Sweden to those which flourish in Spain. In the middle part mineral springs abound; but, though some are of great efficacy, they are little used. The most celebrated, and which have establishments greatly frequented, are the baths of Molitg, Baréges, Bagneres, Arles, Vernet, La Preste, Ax, Cambo, Cauterets, Nossa, Olette, Nyer, and the warm springs of the Cerdagne, generally known by the name of Lascaldas. Since the above has been prepared for press our attention has been directed to the Geological Conjectures of Mr. Charpentier, director of the Canton de Vaud mines, respecting the original form and construction of the Pyrenees. The following is an abstract of them as given in his Essai sur la Constitution Geogrostique des Pyrenees, a very sensible and distinguished performance. ‘We have seen,’ says this writer, “that the different formations are disposed in bands parallel to each other and parallel to the general direction of the Pyrenees; that the granite forms only a single band, or, speaking more correctly, a chain or series of protuberances; that each of the other formations constitutes in general two bands, one of which is situated to the north, the other to the south of the granitic chain, resting upon it in the order of their relative antiquity; that many of these granitic protuberances are separated from one another § valleys, while others, on the contrary, are, as it were, agglutinated by rocks of later origin, which have filled up the spaces or vacuities by which they were formerly separated; and, lastly, that it is commonly in the spaces which exist between two great protuberances that we observe the bands that occur to the south of the granitic chain, touching and mingling with those which occur to the north. These facts entitle us to presume that the granitic formation, comprising that of mica-slate and primitive limestone, formed originally an uninterrupted chain, or rather an elongated line, having a direction from south-east to north-west, and being of a height, whether absolute or relative, much greater than at the present day; that at a period anterior to the formation of the other rocks which recline upon it, this granitic chain has undergone degradations caused by a power . Currents of water) which, acting |. rom south to north, or from north to south, has broken its ridge in many parts, scooped it out to a great depth, and changed it into a series of more or less isolated eminences; that the rocks formed after this revolution have been applied on each side against this central granitic chain, have filled up its deepest hollows, and have even cover

ed its lowest protuberances; and that, lastly, immediately after this revolution, the ridge of the primitive formation was, without doubt, at the same time that of the whole chain of the Pyrenees. ‘Now, as we observe at the present day that the ridge of the Pyrenees, with the exception of a small number of places, is no longer the ridge of the granitic chain, which is found removed at some distance to the north; but that this geographic ridge is composed of more modern rocks, which generally surpass the primitive formation in height, we are naturally led to presume that the Pyrenees have undergone a second very considerable degradation. The disposition of the rocks, and the external form of the mountains, appear to determine the period of this revolution. It is probable that it has taken place after the formation of the transition deposite, and before the excavation of the presently existing valleys, and consequently before the deposition of the trap formation, which, as we shall see in the sequel, appears to be of a very late origin. ‘Observation tends to induce a presumption that this degradation has principally attacked the ridge then existing, and all the northern aspect of the chain. We shall represent by a diagram the results which have given rise to this supposition. “The figure shows the vertical and transverse

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section A B C of the Pyrenees in the direction of their breadth, such as we presume it to have been before these mountains underwent the degradation of which we have been speaking. We see in this section the two declivities A B and A D of equal size; the granite occupying the centre, and forming the ridge of the chain; the transition formation, and the secondary formation, distributed in nearly equal quantities upon the south and north sides, resting upon the granite. Let us now suppose that all the portion of these mountains situated between A, B, and C, has been destroyed by the effect of some power acting from north to south, in such a manner that there remains only the part situated between C, B, and D. “The necessary consequence of this degradation would be a considerable change in the external form of the whole chain Öf mountains, and especially in the disposition and distribution of the rocks with relation to the external form of the chain; in short, this revolution would produce a multitude of results and accidents which are observed in the Pyrenees, and of which we shall recapitulate the chief. “There would result from the destruction of all the parts situated between A, B, and C, 1st, That the ridge would be lowered; and, further, that its position would be removed more to the south, and that consequently the northern aspect B, C, would become longer and more sloping than the southern one B D, 2dly, That the granite, including the other primitive rocks, would no longer form the ridge of the central chain, to the north of which it would occur at a short distance. 3dly, That the southern bands of the secondary and transition formations would obtain a height which would in general surpass that of the granite and that of all the other rocks situated to the north of the primitive formation. 4thly, That these two southern bands would, in general, form the ridge of the whole system. 5thly, That the transition formation would be much more diffused, or, at least, would appear to a much greater extent, upon the north side than upon the southern declivity. 6thly, That the secondary formation would occupy all the southern declivity, while, on the northern side, it would only form the low mountains at the foot of the chain. ‘We here see how well the necessary results of the supposition which we have admitted accord with the actual phenomena. Several other observations would further lead us to presume, that, independently of the great revolution of which we have been speaking, the northern part of the Pyrenees must have undergone, previously to the formation of the present valleys, a new degradation of considerable extent; such, for example, are the generally softer and thore rounded forms of the northern, compared with the southern mountains; the more considerable number of basins in the French valleys than in those of the Spanish side; and the immense deposites of transported rocks, of which the soil of the plains . extend from the north side of the Pyrenees is formed.' PYRIFORMIS, banksia, in botany, a species of BANKsia, which see. It was unknown to Linné; and Gaertner, who has mentioned it, gives no specific character of it. It has solitary flowers, ovate downy capsules, and lance-shaped entire smooth leaves: caps. larger than in any other known species. PYRMONT, a district in the north-west of Germany, between Hanover in the north, and the Prussian government of Minden, in Westphalia, in the south. It belongs to prince Waldec, with the title of a county, but has an area of only thirty-six square miles, with 4300 inhabitants; of the prince's income (about £10,000), the larger half arises from the mineral springs of PyRMont, the chief town of the above principality. It contains 2000 inhabitants, and is situated in a pleasant valley, with public walks, and houses adapted to the accommodation of visitors. Thirty-three miles S.S. W. of Hanover, and sixteen south-east of Rinteln. PYROCITRIC Acid, in chemistry. When citric acid is put to distil in a retort, it begins at first by melting; the water of crystallisation sepa

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rates almost entirely from it by a continuance of .

the fusion; then it assumes a yellowish tint, which gradually deepens. At the same time there is disengaged a white vapor which goes over, to be condensed in the receiver, Towards

the end of the calcination a brownish vapor is seen to form, and there remains in the bottom of the retort a light very brilliant charcoal. The product contained in the receiver consists of two different liquids. One of an amber-yellow color, and an oily aspect, occupies the lower part; another, colorless, and liquid like water, of a very decided acid taste, floats above. After separating them from one another, we perceive that the first has a very strong bituminous odor, and an acid and acrid taste; that it reddens powerfully the tincture of litmus, but that it may be deprived almost entirely of that acidity by agitation with water, in which it divides itself into globules, which soon fall to the bottom of the vessel, and are not long in uniting into one mass, in the manner of oils heavier than water. In this state it possesses some of the properties of these substances; it is soluble in alcohol, ether, and the caustic alkalis. However, it does not long continue thus; it becomes acid, and sometimes even it is observed to deposit, at the end of some days, white crystals, which have a very strong acidity; if we then agitate it anew with water, it dissolves in a great measure, and abandons a yellow or brownish pitchy matter, of a very obvious empyreumatic smell, and which has much analogy with the oil obtained in the distillation of other vegetable matters. The same effect takes place when we keep it under water; it diminishes gradually in volume, the water acquires a sour taste, and a thick oil remains at the bottom of the vessel. This liquid may be regarded as a combination (of little permanence indeed) of the peculiar acid with the oil formed in similar circumStances. This acid is white, inodorous, of a strongly acid taste. It is difficult to make it crystallise in a regular manner, but it is usually presented in a white mass, formed by the interlacement of very fine small needles. Projected on a hot body it melts, is converted into white very punent vapors, and leaves some traces of carbon. When heated in a retort, it affords an oily-looking acid, and yellowish liquid, and is partially decomposed. It is very soluble in water and in alcohol; water at the temperature of 10° C. (50°F.) dissolves one-third of its weight. The watery solution has a strongly acid taste, it does not precipitate lime or barytes water, nor the greater part of metallic solutions, with the exception of acetate of lead and protonitrate of mercury. With the oxides it forms salts possessing properties different from the citrates. The pyrocitrate of potash crystallises in small needles, which are white, and unalterable in the air. It dissolves in about four parts of water. Its solution gives no precipitate with the nitrate of silver, or of barytes; whilst that of the citrate of barytes forms o with these salts. The pyrocitrate of lime directly formed exhibits a white crystalline mass, composed of needles, opposed to each other in a ramification form. §. salt has a sharp taste. PYROLA, in botany, winter green, a genus of the monogynia order, and decandria class of plants; natural order eighteenth, bicornes: CA1. quinquepartite; petals five: caps. is quinquelocular, opening at the angles. PYROLIGNEOUS Acid, in chemistry, is the destructive distillation of any kind of wood an acid is obtained, which was formerly called acid spirit of wood, and since pyroligneous acid. Fourcroy and Vauquelin showed that this acid was merely the acetic, contaminated with empyreumatic oil and bitumen. See Acetic Acid, CHEMISTRY, and VINEGAR. PYROLITHIC Acid, in chemistry. “When uric acid concretions are distilled in a retort, silvery white plates sublime. These are pyrolithate of ammonia. When their solution is ured into that of subacetate of lead, a pyrolithate of lead falls, which, after proper washing, is to be shaken with water, and decomposed by sulphureted hydrogen gas. The supernatant liquid is now a solution of pyrolithic acid, which yields small acicular crystals by evaporation. By heat, these melt and sublime in white needles. They are soluble in four parts of cold water, and the solution reddens vegetable blues. Boiling alcohol dissolves the acid, but on cooling it deposits it, in small white grains. Nitric acid dissolves without changing it. Hence, pyrolithic is a different acid from the lithic, which, by nitric acid, is convertible into purpurate of ammonia. The pyrolithate of lime crystallises in stalactites, which have a bitter and slightly acrid taste. It consists of 91.4 acid + 8.6 lime. Pyrolithate of barytes is a nearly insoluble powder. The salts of potassa, soda, and ammonia, are soluble, and the former two crystallisable. At a red heat, and by passing it over ignited oxide of copper, it is decomposed, into oxygen 44:32, carbon 28-29, azote 1684, hydrogen 10." PYROMALIC Acid, in chemistry, when malic or sorbic acid, for they are the same, is distilled in a retort, an acid sublimate, in white needles, appears in the neck of the retort, and an acid liquid distils into the receiver. This liquid, by evaporation, affords crystals, constituting a peculiar acid, to which the above name has been given. They are permanent in the air, melt at 118° Fahrenheit, and on cooling form a pearl-colored mass of diverging needles. When thrown on red-hot coals, they completely evaporate in an acrid, cough-exciting smoke. Exposed to a strong heat, in a retort, they are partly sublimed in needles, and are partly decomposed. They are very soluble in strong alcohol, and in double their weight of water, at the ordinary temperature. The solution reddens vegetable blues, and yields white flocculent precipitates with acetate of lead and nitrate of mercury; but produces no o: with lime water. By mixing it with barytes water, a white powder falls, which is redissolved by dilution with water, after which, by gentle evaporation, the pyromalate of barytes may be obtained in silvery plates. These consist of 100 acid, and 185:142 barytes, or, in prime equivalents, of 5.25 +975. Pyromalate of potash may be obtained in feather formed crystals, which deliquesce. Pyromalate of lead forms first a white flocculent precipitate, soon passing into a semi-transparent jelly, which, by dilution and filtration from the

water, yields brilliant pearly looking needles. The white crystals that sublime in the original distillation are considered by M. Lassaigne as a peculiar acid. PYROMETER, from rup, fire, and perpov, measure. To measure those higher degrees of heat to which the thermometer cannot be apo there have been other instruments invented y different philosophers: these are called pyrometers. The most celebrated instrument of this kind, and which has been adopted into general usé, is that invented by the late ingenious Mr. Wedgwood. This instrument is also sufficiently simple. It consists of two pieces, of brass fixed on a plate, so as to be six-tenths of an inch asunder at one end, and three-tenths at the other; a scale is marked upon them, which is divided into 240 equal parts, each one-tenth of an inch; and with this his gauge, are furnished a sufficient number of pieces of baked clay, which must have been prepared in a red heat, and must be of given dimensions. These pieces of clay, thus prepared, are first to be applied cold to the rule of the gauge, that there may no mistake take place in regard to their dimensions. Then any one of them is to be exposed to the heat which is to be measured, till it shall have been completely pe. netrated by it. It is then removed and applied to the gauge. The difference between its former and its present dimensions will show how much it has shrunk; and will consequently indicate to what degree the intensity of the heat to which it was exposed amounted. High temperatures can thus be ascertained with accuracy. Each degree of Wedgwood's pyrometer is equal to 130° of Fahrenheit's. Mr. Wedgwood sought to establish a correspondence between the indications of his pyrometer and those of the mercurial thermometer, by employing a heated rod of silver, whose expansions he measured, as their connecting link. The clay-piece and silver rod were heated in a muffle. When the muffle appeared of a low red heat, such as was judged to come fully within the province of the thermometer, it was drawn forward toward the door of the oven; and, its own door being then nimbly opened by an assistant, Mr. Wedgwood pushed the silver piece as far as it would go. But, as the division which it went to could not be distinguished in that ignited state, the muffle was lifted out, by means of an iron rod passing through two rings made for that purpose with care to keep it steady, and avoid any shake that might endanger the displacing of the silver piece. When the muffle was grown sufficiently cold to be examined, he noted the degree of expansion which the silver piece stood at, and the degree of heat shown by the thermometer pieces measured in their own gauge; then returned the whole into the oven as before, and repeated the operation with a stronger heat, to obtain another point of correspondence on the two scales. The first was at 23° of his thermometer, which coincided with 66° of the intermediate one; and, as each of these last had been before found to contain 20° of Fahrenheit's, the 66° will contain 1320; to which add 50, the degree of his scale to which the (0) of the intermediate thermometer was adjusted, and the sum 1370 will be the d of Fahrenheit's corresponding to his 24°. #. second point of coincidence was at 64° of his, and 92° of the intermediate; which 92° being, according to the above proportion, equivalent to 1840 of Fahrenheit, add 50 as before to this number, and his 64° is found to fall upon the 1890° of Fahrenheit. It appears hence that an interval of 4° upon Mr. Wedgwood's thermometer is equivalent to an interval of 520° upon that of Fahrenheit; and, consequently, one of the former to 130° of the latter; and that the (0) of Mr. Wedgwood corresponds to 10771% of Fahrenheit. From these data it is easy to reduce either scale to the other through their whole range; and from such reduction it will appear, that an interval of nearly 480° remains between them, which the intermediate thermometer serves as a measure for; that Mr. Wedgwood's includes an extent of about 32,000 of Fahrenheit's degrees, or about fifty-four times as much as that between the freezing and boiling points of mercury, by which mercurial ones are naturally limited; that if the scale of Mr. Wedgwood's thermometer be produced downward in the same manner as Fahrenheit's has been supposed to be produced upward, for an ideal standard, the freezing point o water would fall nearly on 8° below (0) of Mr. Wedgwood's, and the freezing F. of mercury a little below 83°; and, that, therefore, of the extent of now measurable heat, there are about five-tenths of a degree of his from the freezing of mercury to the freezing of water; 8° from the freezing of water to full ignition; and 160° above this to the highest degree he has hitherto attained. Mr. Wedgwood concludes his account with the following table of the effects of heat on different substances, according to Fahrenheit's thermometer and his own :

Fahr. Wedg. Extremity of the scale of his thermometer . . . .3227.7° 240 Greatest heat of his small air furnace . . . . . 21877 160 Cast-iron melts . . . . 17977 130 Greatest heat of a common smith's forge . . . . 17327 125 Welding heat of iron greatest 13427 95 Welding heat of iron least. 12777 90 Fine gold melts 5237 32 Fine silver melts . 4717 28 Swedish copper melts . 4587 27 Brass melts . . . . . 3807 Q I Heat by which his enamel colors are burnt on . 1857 6 Red heat fully visible in day-light . . . . . 1077 0. Red heat fully visible in the dark - - - - - - 947 – 1 Mercury boils. 600 3; Water boils 212 6 ##, Vital heat 97 7 f.; Water freezes . - - 32 8 on Proof spirit freezes . . . 0 8 fo,

The point at which mercury congeals, consequently the limit of mercurial thermometers, about . . . 40 8 # PYROMUCIC Acid. This acid, discovered in 1818 by M. Houton Labillardière, is one of the products of the distillation of mucic acid. When we wish to procure it, the operation must be performed in a glass retort furnished with a receiver. The acid is formed in the brown liquid, which is produced along with it, and which contains water, acetic acid, and empyreumatic oil; a very small quantity of the pyromucic acid remaining attached to the vault of the retort under the form of crystals. These crystals, being colored, are added to the brown liquor, which is then diluted with three or four times its quantity of water, in order to throw down a certain portion of oil. The whole is next filtered, and evaporated to a suitable degree. A great deal of acetic acid is volatilised, and then the new acid crystallises. On decanting the mother waters, and concentrating them farther, they yield crystals anew ; but, as these are small and yellowish, it is necessary to make them undergo a second distillation to render them susceptible of being perfectly purified by crystallisation; 150 parts of mucic acid furnish about sixty of brown liquor, from which we can obtain eight to ten of pure pyromncie acid. This acid is white, inodorous, of a strongly acid taste, and a decided action on litmus. Exposed to heat in a retort it melts at the temperature of 266° Fahrenheit, then volatilises, and condeuses into a liquid, which passes on cooling into a crystalline mass, covered with very fine needles. It leaves very slight traces of residuum in the bottom of the retort. On burning coals, it instantly diffuses white pungent vapors. Air has no action on it. Water, at 60° dissolves one-twenty-eighth of its weight. Boiling water dissolves it much more abundantly, and on cooling abandons a portion of it, in small elongated plates, which cross in every direction. PYROPHORUS. By this name is denoted an artificial product, which takes fire or becomes ignited on exposure to the air. Hence, in the German language, it has obtained the name of luft-Zunder, or air-tinder. It is prepared from alum by calcination, with the addition of various inflammable substances. Homberg was the first that obtained it, which he did accidentally in the year 1680, from a mixture of human excrement and alum, upon which he was operating by fire. The preparation is managed in the following manner:—Three parts of alum are mixed with from two to three parts of honey, flour, or sugar; and this mixture is dried over the fire in a glazed bowl, or an iron pan, diligently stirring it all the while with an iron spatula. At first this mixture melts, but by degrees it becomes thicker, swells up, and at last runs into small dry lumps. These are triturated to powder, and once more roasted over the fire, till there is not the least moisture remaining in them, and the operator is well assured that it can liquefy no more: the mass now looks like a blackish powder of charcoal. For the sake of avoiding the previous above mentioned operation, from four to five of burned alum may be mixed directly with two of charcoal powder. This powder is poured into a phial or matrass, with a neck about six inches long. The phial, which however must be filled three-quarters full only, is then put into a crucible, the bottom of which is covered with sand, and so much sand is put round the former that the upper part of its y also is covered with it to the height of an inch: upon this the crucible, with the phial, is put into the furnace, and surrounded with red-hot coals. The fire, being now gradually increased till the phial becomes red-hot, is kept up for the space of about a quarter of an hour, or till a black smoke ceases to issue from the mouth of the phial, and instead of this a sulphureous vapor exhales, which commonly takes fire. The fire is kept up till the blue sulphureous flame is no longer to be seen;

upon this the calcination must be put an end to, and the phial closed for a short time with a stopper of clay or loam. But, as soon as the vessel is become so cool as to be capable of being held in the hand, the phial is taken out of the sand, and the powder contained in it transferred as fast as possible from the phial into a dry and stout glass made warm, which must be secured with a glass stopper. We have made a very good pyrophorus by simply mixing three parts of alum with one of wheat-flour, calcining them in a common phial till the blue flame disappeared; and have kept it in the same phial, well stopped with a good cork when cold. If this powder be exposed to the atmosphere, the sulphuret attracts moisture from the air, and generates sufficient heat to kindle the carbonaceous matter mingled with it.

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PYROTECHNY, n.s. Fr. pyrotechnie. The art of managing fire, or making fire-works.

Great discoveries have been made by the means of pyrotechny and chymistry, which in late ages have attained to a greater height than formerly. Hale's Origin of Mankind.

PyRotechNY, of Greek. arup, fire, and rexvn, art, is a term that has been applied to all kinds of artificial fire-works, including those of a military description; but of late it has been more commonly restricted to those fire-works which are constructed for amusement, or are used in public demonstrations of joy: and it is in this sense we shall consider it in this article.

These are inventions which, though they seem to have been for ages familiar to the Chinese and other nations of the eastern world, were brought at a recent period only into Europe by way of Italy; and the Italian and French artists long bore away the palm in their construction. The late Sir William Congreve, however, at the period of the peace of 1815, seemed suddenly to rise like one of his own rockets, above our foreign competitors; and with the aid of his majesty's parks, the public purse, the sheet of water in St. James's park, and the never-to-be-forgotten Chinese bridge over the said water, to have attained the most brilliant honors in this art. We believe all his principal devices will be found included in the descriptive account of modern fire-works here following :

PART I.

SMALLER AND MISCELLANEOUS FIREWORKS.

1. Of the Chinese fire.—In honor of the Chinese we begin with the brilliant fire sometimes called Chinese fire. Iron filings, when thrown into the fire, inflame and emit a strong light. This property, discovered perhaps by chance, gave rise to the idea of rendering the fire of rockets, and

other pyrotechnical inventions, much more brilliant than when gunpowder, or the substances of which it is .. are alone employed. Nothing is necessary but to take iron filings, very clean and free from dust, and to mix them with the ordinary composition. It must, however, be observed, that works of this kind will not keep longer than a week; because the moisture contracted by the saltpetre rusts the iron filings.

The Chinese have long been in possession of a method of rendering this fire much more brilliant and variegated in its colors; and we are indebted to father d'Incarville, a jesuit, for having made it known. It consists in the use of a simple ingredient, namely, cast iron reduced to a powder more or less fine: the Chinese gave it a name which is equivalent to that of iron sand. To prepare this sand take an old iron pot, and, having broken it to pieces on an anvil, pulverise the fragments till the grains are not larger than radish seed; then sift them through six graduated sieves, to separate the different sizes; and preserve these six different kinds in a very dry place, to secure them from rust, which would render this sand absolutely unfit for the proposed end. We must here remark that the grains which pass through the closest sieve are called sand othe first order; those which pass through the next in size, sand of the .."order; and so on.

This sand, when it inflames, emits a light exceedingly vivid. It is very surprising to see fragments of this matter no bigger than a poppy seed form all on a sudden luminous flowers or stars, twelve and fifteen lines in diameter. These flowers are also of different forms, according to that of the inflamed grain, and even of different colors, according to the matters with which the grains are mixed. Rockets which contain the finest sand will not keep longer than eight days, and those which contain the coarsest, fifteen. The following tables exhibit the proportions of the differentingredients for rockets of from twelve to thirty-six pounds.

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