PYROTECHNY Chinese or Japanese Fire.-This composition, which may be either rammed into cases of an inch in diameter, or folded up in quantities of about 1 or 1 grain in slips of tissue paper, consists of Nitrate of potassium 34 parts PYROXYLIN various processes adopted in the construction a limpid liquid, of a penetrating odour, parof fireworks, Ure's Dictionary of Arts, &c. art. taking of that of alcohol. Its taste is hot and Fireworks.') pungent. Its specific gravity at 0° C. is 8142. It is very inflammable, and burns with a pale flame resembling that of alcohol. It boils at from 60° to 66 5° C.; the density of its vapour compared with hydrogen is 16; CH,O= 32=16. Methylic alcohol is the hydrate of methyl, and forms the first term of the methylic series of homologous alcohols, CH2+20. Thus methyl 1 part alcohol CH,O, ethylic alcohol C2H.O. It 1 39 is not altered by exposure to air or light; but These ingredients should be well incorporated, when subjected to the slow action of platinumafter being first passed through a fine sieve. black, formic acid is the chief product and stands If put into a case, the mixture burns slowly, in the same relation to it that acetic acid does throwing out splendid coruscating sparks which, to ethylic alcohol, CH ̧0+02 = CH20, + OH2. from some fancied resemblance to the rowel of Formic acid is similarly the first term of the a spur, caused this mixture to be formerly corresponding series of acids C-H2O. The called spur fire. These magnificent sparks are pure body is neutral, and mixes in all properhaps seen to best advantage when the com- portions with water, alcohol, and ether, without position is enclosed in tissue paper, as above becoming turbid. Its solvent powers, in regard described. These charged papers have re- to salts, closely resemble those of alcohol; it cently become known under the name of dissolves the resins, and may be used as a subJapanese matches. stitute for alcohol in almost all varnishes. is a powerful antiseptic, and preservative of animal matter. PYROTECHNY. In Military Art, the science of the manufacture of artificial fireworks, and all combustible materials, including the compositions for rockets, fuses, carcasses, &c. &c., together with their use and application. Pyroxanthin (Gr. wûp, and faveos, yellow). Eblanin. A crystalline yellow derivative of the action of alkalies upon wood-tar. Pyroxene (Gr. wûp, and ¿évos, a guest). A mineral isomorphous with Hornblende, but differing from it in containing a smaller quantity of silica, in being less fusible, and in having a higher specific gravity. The name indicates that it is a guest in the domain of fire, or that it is supposed to have pre-existed in the lava in which it is contained, and is not therefore a result of crystallisation consequent on the cooling of the mass. [AUGITE.] It Methylated Spirit.-A mixture of 90 per cent. of alcohol and 10 per cent. of methylic alcohol is much used in the arts and manufactures, as well as in medicine and chemistry, as a substitute for rectified spirit. Pyroxylin. The manufacture of this substance for military purposes, and its composition when so prepared, are noticed under the article GUN COTTON. In the chemical laboratory the following process may be resorted to for its production. Dry and clean carded cotton-wool is steeped in a mixture of three volumes of nitric acid (sp. gr. 1·5) with five of sulphuric acid; the mixture is allowed to cool, and small portions of cotton should be used at a time, so as to avoid elevation of temperature. Pyroxylic Spirit, Wood Spirit, or Me- In ten or twenty minutes the cotton may be thylic Alcohol. When wood is subjected withdrawn (the excess of acid pressed out), to destructive distillation there is formed, and thoroughly washed in water containing a besides tar, acetic acid, and other products, little ammonia; it is then cautiously dried, at a variable portion, but not amounting on a temperature not exceeding 200° Fahr. 100 an average to more than about 1 per cent., parts of cotton thus treated yield about 177 of of an inflammable and volatile liquid. This dry gun cotton. Clean paper, the purer varieties may be separated, to a certain extent, from of sawdust, and other forms of ligneous matter, the water and acetic acid, by distillation and produce similar compounds. Pyroxylic paper separation of the first products. These, re- is remarkable for the intensity of its electricity distilled and rectified over quicklime, afford when slightly rubbed. Well-prepared pyroxythe pyroxylic spirit or methylic alcohol of lin resembles the original cotton in appearance, commerce. It should be neutralised, by sul- but is more harsh and brittle, and highly phuric acid, previous to its last rectification. electric. Its extreme combustibility is very reAn excess of chloride of calcium is then added, markable. Inflamed in the open air it flashes and the mixture is distilled in a water-bath off without smoke or residue; it takes fire at so long as any volatile matter goes over. a much lower temperature than that required A compound of wood-spirit with chloride of for the ignition of gunpowder, and its combuscalcium remains in the retort, to which a quan- tion is more rapid. The temperature at which tity of water, equal to that of the original gun cotton is inflamed is about 277° Fahr., but spirit, is added, and the distillation then con- the different varieties of it no doubt require tinued. The product which is now obtained, different temperatures for their ignition. When and which is pure methylic alcohol diluted by substituted for gunpowder in firearms, the exa little water, may be dehydrated by a final treme suddenness of its explosion would be apt distillation off quicklime. Methylic alcohol is to burst the barrel, unless precautions were PYRRHA taken to prevent the simultaneous ignition of the whole charge. When this is done, however, it has now been shown that pyroxylin can be safely and with great advantages substituted for gunpowder in fowling-pieces. It is not deteriorated in damp air, or even (when subsequently dried) by immersion in water; and, weight for weight, its explosive force is between three and four times greater than that of gunpowder. The extreme rapidity of its combustion is well shown by placing a flock of it upon a small heap of gunpowder, where it may be exploded by a hot wire with out kindling the powder. Aqueous vapour, carbonic oxide, carbonic acid, and nitrogen, are the only products of its combustion in a closed space, but in the open air it forms also traces of nitrous acid. Under the name of collodion, a solution of pyroxylin in a mixture of alcohol and ether is largely used by photographers. For such purposes Mr. Nicol recommends the following formula. Ten ounces, by measure, of sulphuric acid (1840), and fire ounces, by measure, of nitric acid (1370), are to be well mixed, and two fluid drachms of water added. When the mixture has cooled to about 130°, place in it, tuft by tuft, well pulled out, five drachms of clean cotton. Each tuft should be penetrated by the acid as it is immersed, and kept in for ten minutes, then removed, well washed, and dried. This compound is soluble in a mixture of alcohol and ether, and the solution leaves, on evaporation, a smooth transparent film. PYTHAGOREANS the Azores. It is probably columbate of Zirconia coloured by the oxides of iron, uranium, and manganese. Pyrrhonists. The followers of Pyrrho, a philosopher of Elis, and disciple of Anaxarchus, who flourished about 300 B. c. Their tenets, which have come to us only through the reports of unfriendly writers, are said to have been so absurdly sceptical, that they would not put even as much confidence in the senses as was necessary for the preservation of their existence; but this seems partly refuted by the age at which Pyrrho himself died, which was ninety years. There is a summary of the doctrines of Pyrrhonism in the 2nd vol. of the historical part of the Encyc. Metropolitana; see also Hallam, Literary History, part ii. ch. iii. § 17, and ch. iv. § 8, and part iii. ch. iii. § 87. [SCEPTICISM.] Pyrrhotine (Gr. wuppórns, redness). Magnetic Iron Pyrites. A sulphide of iron composed of 60-5 per cent. of iron and 39.5 sulphur. It generally occurs massive and amorphous, but sometimes crystallised, in irregular and variously modified six-sided prisms. The colour, which is bronze-yellow, reddish, or brownish, is liable to become speedily tarnished on exposure to the air. It is found in Cornwall, Devonshire, and Cumberland, in North Wales, and Scotland. In Ireland it is met with of a bronze colour near Leahtown, Donegal. [MAGNETIC PYRITES.] Pyrrol. An empyreumatic oil formed during the destructive distillation of bone. Pyrus (Lat. pirus, a pear-tree). The genus The composition of pyroxylin varies with the of Pomacea or Rosacea, to which belong the mode of preparation. It is generally regarded Apple and Pear. In these fruits the ovaries as a substitution compound in which peroxide become united, and form with the calyx-tube a of nitrogen (NO,) replaces one or more atoms fleshy mass enclosing about five leathery or of the hydrogen of the cotton-fibre. According cartilaginous cells, within which are one or two to Hadow, the most explosive variety (insoluble pips. This consistence of the cells is the chief in a mixture of alcohol and ether) may be distinction between Pyrus and Crategus, the represented by the formula C,,H2(NO2),O15, cells of the latter being hard and bony. Besides and the less explosive variety used in making the Apple, P. Malus, and Pear, P. communis, the collodion, and therefore soluble in a mixture genus includes the Service-tree, P. Sorbus, the of alcohol and ether, as CH(NO2)015 So White Beam-tree, P. Aria, and the Mountain that in the former nine, and in the latter eight atoms of the hydrogen of the cotton are replaced by peroxide of nitrogen, assuming cotton fibre as CH30015 Pyrrha. In Mythology. [DEUCALION.] Pyrrhic Dance. A species of warlike dance called by the Romans Pyrrhica Saltatio, said to have been invented by Pyrrhus to grace the funeral of his father Achilles. This dance consisted chiefly in such an adroit and nimble turning of the body as represented an attempt to avoid the strokes of an enemy in battle, and the motions necessary to perform it were looked upon as a kind of training for the field of battle. This dance is supposed to be described by Homer as engraved on the shield of Achilles. Lord Byron describes the Suliotes as still performing this dance (Childe Harold). Pyrrhite (Gr. Tupfós, yellow). A mineral occurring in minute octahedrons of an orangeyellow colour, at Alabaschka in Siberia, and Ash or Rowan, P. Aucuparia. From the fruit of the latter a jelly is made which is highly esteemed as an adjunct to venison. [APPLE; PEAR.] An Pyruvic Acid. Pyroracemic acid. acid discovered by Berzelius amongst the products of the destructive distillation of racemic and of tartaric acid. Pythagorean Theorem. In Geometry, the theorem which forms the forty-seventh proposition of Euclid's first book, and according to which the sum of the squares on the sides of a right-angled triangle is equal to the square on the hypothenuse. Pythagoreans. The followers of Pythagoras, a native of Samos, said to have been the first Greek who assumed the title of a philosopher. The date of his birth and the extent of his scientific travels are matters of great uncertainty (Sir G. C. Lewis, On the Credibility of Early Roman History, vol. i. PYTHAGOREANS PYXIS NAUTICA For the character and working of the Pythagorean brotherhoods, see Grote's History of Greece, part ii. ch. xxxvii. An account of the astronomical theories of Pythagoras and his followers is given by Sir G. C. Lewis, Astronomy of the Ancients, p. 13, &c. See also Thirlwall's History of Greece, vol. ii. c. xii. ; Ritter's History of Philosophy, b. iv.; Boeckh's Philolaus, &c. Pythia (Gr.). The name of the priestess of the Delphian oracle of Apollo. [ORACLE.] p. 451; Astronomy of the Ancients, 123-269); | right and left, male and female, still and but he is said finally to have fixed his abode moved, straight and curved, light and darkat Crotona, one of the Dorian colonies in the ness, good and evil, square and oblong. south of Italy. He here attached to himself a large number of youths of noble descent, whom he formed into a secret fraternity for religious and political as well as philosophical purposes; and by their assistance produced many beneficial changes in the institutions of Croton and the other Græco-Italian cities. Of the strictly philosophical tenets of the Pythagoreans very imperfect records are preserved. Many of the doctrines ordinarily imputed to them are evi- The doctrine of METEMPSYCHOSIS, or the dently the fabrication of the later Pythago- transmigration of souls through different orders reans, a class of visionaries who lived during of animal existence, is the main feature by which the decline of the Roman empire. One point the Pythagorean philosophy is popularly known. is sufficiently evident, that the Pythagoreans It is, however, by no means certain that the were the greatest mathematicians of their genuine Pythagoreans held this doctrine in a time, and that they sought in the study of literal sense. It may have been only a mythimathematical relations that solution of the cal way of communicating their belief in the principal philosophical problems for which individuality of the soul and its existence after their contemporaries, the Ionic and Eleatic death. philosophers, sought, the first in physical, the others in ontological hypotheses. The relations of space and quantity, as they are the most obvious, are also the most definite forms, in which the laws of the outward world can present themselves to this faculty. Hence, as the atomic philosophers have endeavoured to explain all things by a diversity in the figure of their ultimate parts, the Pythagoreans seem to have found, in the number and proportions of those parts, the true essence of the things themselves. Having proceeded thus far, they went a step farther. They perceived that the universe and its parts are obedient to certain laws, and that these laws can be expressed by numbers. By a mistake prevalent during every period of speculation, they mistook the necessary conditions of a thing's subsistence for the essence of that thing itself; and at once pronounced that numerical relations were not merely all that could be understood in outward phenomena, but were, in fact, all that was real in them. Units of number grew gradually into points in space, and these into material atoms. To every order of existence, even to many abstract conceptions, a distinct number was assigned. God is represented as the original unity; the human soul, the earth, the planets, the animal creation have each their own peculiar arithmetical essence; as have also the abstractions justice, opportunity, opinion, &c. The outlines of a duallistic scheme are discernible in a singular table of opposites (auGroixía), preserved to us by Aristotle, in which the two principles of the universe are successively represented under the form of limit and the unlimited, odd and even, one and many, 154 Pythian Games. One of the four great national festivals of Greece, celebrated every fifth year in honour of Apollo, near Delphi. Their institution is variously referred to Amphictyon, son of Deucalion, founder of the council of Amphictyons, and Diomedes, son of Tydeus; but the most common legend is that they were founded by Apollo himself, after he had overcome the dragon Python. The contests were the same as those at Olympia, and the victors were rewarded with apples and garlands of laurel. [DELPHI.] Python (Пúowy). In Greek Mythology, the name of the dragon slain by Apollo. [PHOEBUS; PERSEUS.] The name was interpreted by the word now, to rot, because its dead body was left to rot at Delphi; but this explanation is of no more value than that which professes to account for the name Lycaon. [RISHIS.] In Teutonic myths, Python reappears as Fafnir. [MYTHOLOGY, COMPARATIVE; EDIPUS; PERSEPHONE; SIGURDR.] PYTHON. In Zoology, the name of a genus of large Ophidian reptiles, having anal hooks, and a double series of sub-caudal scutæ. The Pyx (Gr. #vέís, a box of box-wood). name given to the box in which the host is kept by the Roman Catholic priesthood. Pyx, Trial of. [COINAGE.] Pyxidium (Gr. Tugídiov, dim. of #ugis). In Botany, a fruit which divides circularly into a lower and upper half, of which the latter acts as a kind of lid, as in the Pimpernel. Pyxis Nautica. The Mariner's Compass. A constellation of the southern hemisphere formed by Lacaille. QUADRANT OF ALTITUDE Q. In all the languages in which it is used this letter is invariably followed by u, the combination being represented in English pronunciation by the letters kw, as in quote. Qis used as an abbreviation for question; Qy. for query; QED. for quod erat demonstrandum, which was to be demonstrated, &c. tion. The instrument is variously contrived and fitted up, according to the purpose for which it is intended; but it consists essentially of a limb or are of a circle equal to the fourth of the circumference, and divided into 90°, with subdivisions. The mural quadrant is of considerable size (six or eight feet radius, for Quader Sandstone. The cretaceous rocks example), the axis of which moves in a wall or of the north of Germany chiefly consist of solid piece of masonry. [MURAL CIRCLE.]sandstones, called Quader sandstones. There Ptolemy, in the Almagest, describes a quadrant are two divisions-the Upper Quader, corre- with which he determined the obliquity of the sponding nearly in geological age to the main ecliptic. Tycho Brahe had a large mural quadbody of the chalk in England and Europe, and rant for observing altitudes, and others which the Lower Quader, which represents our upper revolved on a vertical axis for measuring azigreensand and firestone. These German beds muths. Picart, in his measurement of the earth, are not without calcareous matter, but it is used a quadrant for his terrestrial angles. In chiefly present as a cementing medium. They 1725 a mural quadrant, by Graham, was erected are fossiliferous towards the base. Parts of in the Royal Observatory at Greenwich, which, them are much used as building material, and in 1750, was replaced by Bird's quadrant, with are well adapted for this purpose. which Bradley made his celebrated observaQuadragesima (Lat. fortieth). In the tions. The quadrant has, however, of late Calendar, a term applied to the time of Lent, years been entirely superseded by the mural' because it consists of about forty days. Quad- circle; it having been found that the circle, on ragesima Sunday is the first Sunday in Lent, account of the symmetry of its form, and the and about the fortieth day before Easter. Quadrangle (Lat. quadrangulus, fourcornered). A figure with four angles and four sides; in short, a quadrilateral. This is the ordinary acceptation of the term. In modern geometry, however, a quadrangle or tetragon denotes a system of four points (angles or corners), whilst a quadrilateral or tetragram is regarded as a system of four lines. [QUADRILATERAL.] A quadrangle is regarded as having six sides or lines through two angles. Thus the broken lines in the figure are the sides of the quadrangle a, b, c, d, and a, B, y, are the three intersections of opposite sides, which latter are sometimes called the diagonal points of the complete quadrangle. One of the most important properties of the quadrangle is that the rays joining any one of these three diagonal points with the other two are harmonic conjugates with respect to the sides which pass through the first point. Thus a (a b By), B(abya), y(ad aß) are harmonic pencils. Quadrans (Lat.). A division of the Roman as, consisting of one-fourth of it, or three ounces when the as was of its full weight. [AS; FARTHING; PENNY; TERUNCIUS.] advantage which it possesses of allowing the readings to be made at different parts of the limb, is an instrument much more to be relied on. [MURAL CIRCLE.] Hadley's quadrant, in its principle and application, is the same as the sextant, by which it has been superseded. [SEXTANT.] For further information respect ing the quadrant, see Lalande, Astronomie, s. 2,311; Vince's Practical Astronomy; Pearson's Practical Astronomy; and the Penny Cyclopædia. QUADRANT. In Geometry, the fourth part of a circle; an arc of ninety degrees. QUADRANT. In Gunnery, an instrument occasionally used for regulating the elevation: of pieces of ordnance. It consists of two bars of wood or brass, at right angles to each other, with an arc between them divided into degrees. A plumb line hangs from the angle at which the bars meet. One of the bars being placed in the bore of the piece, the degree on the arc intersected by the plumb line shows the elevation. Quadrant of Altitude. An appendix to an artificial globe, consisting of a thin pliable slip of brass, which is applied to the globe, and used as a scale for measuring the distances between points in degrees. It is graduated into 90°, the degrees being of the same length as those on one of the great circles of the globe. At the end where the division terminates a nut is riveted on, and furnished with a screw, by which it is attached to the brass meridian of the globe at any point. This point being placed in the zenith, and the quadrant applied to the globe, its zero coincides with the horizon, and consequently the altitude of any point along its graduated edge is indicated by the corre Quadrant. A mathematical instrument, formerly much used in astronomy and naviga- sponding division. tion from the position AL, through the different positions MN, mn, &c., so as to arrive at CB at the same instant that CK coincides with CB; then the continual intersection of The solution of a pure quadratic is obvious; the revolving radius and the parallel line will trace the quadratrix APQ. From this mode of describing the curve, it is easy to see how it may be applied to divide an angle into any number of equal parts. Let it be required, for example, to trisect the angle AC k. Having applied the quadratrix to CA, take AM equal to a third of Am, and through M draw M N perpendicular to AC, meeting the curve in P; join CP, and the angle ACP is equal to one-third of ACk; for by the nature of the quadratrix AM: Am:: AK: Ak. The application of this curve to the quad- : rature of the circle depends on the property that the line CQ is a third proportional to the quadrantal arc A B, and the radius. Hence C B2 the arc AB: and consequently the area CQ' = If the quadratrix be continued beyond A, without the circle, it will consist of a series of 26, infinite hyperbolic branches, cutting the axis CA produced, in points which are separated from each other by a space equal to 2 A C. a and their product This property is a general one [THEORY OF EQUATIONS], and from it is deduced the following simple rule for forming the quadratic whose roots are two given numbers. For the absolute term of the equation, take the product of the given roots, for the coefficient of r take the negative sum of these roots, and let r2 have the coefficient unity. Thus the equation whose roots are 2 and - 3 is 6=0. Other curves may be formed in a similar manner, by which the quadrature of the circle would be obtained. Thus, instead of supposing the lines M N, m n to be intersected by the radiants CK, Ck, we may suppose straight lines drawn from Kk parallel to A C, intersecting MN, mn in r and s; these intersections form a different curve, which is called the Quadratrix of Tschirnhausen. Let A M =x, MP=y, and A C a; then sincera AK: AB, or, we have A K Hence the equation of the quadratrix of Dinostratus is = Tx 2 a The expression bac, under the radical sign, is called the discriminant of the equation. When it has a positive value, the roots are real and unequal; when it vanishes, the two roots are real and equal; and when it has a negative value, these roots are impossible or and that of the quadratrix of Tschirnhausen is imaginary. [DISCRIMINANT.] Quadratic Form. [QUADRIC.] Quadratrix. In Geometry, a transcendental curve, by means of which the quadrature of curvilinear spaces can be determined mechanically. The best known of these curves is the Quadratrix of Dinostratus, so called from its π X 2 a y = (a-x) tan ; TX y= = a sin Quadrats (Lat. quadratus, squared). In Printing, pieces of metal of the depth of the body of the respective sizes of types, and lower 1 |