Pyrar'gillite (Gr. pyr, and argillos clay), a mineral consisting of potash, soda, silica, alumina, oxide of iron, magnesia, and water: sp. gr. 2'50; H = 3.5.

Pyrene'ite, in mineralogy, a black variety of garnet, found in the Pyrenees, embedded in primitive limestone.

Pyretics (Gr.), medicine for fevers. Pyretology (Gr.), a discourse on fevers. Pyrites (Gr.), fire-stone; a sulphuret of iron or other metal. -Pyretology, a treatise on pyrites.

Pyro-acetic Spirit, in chemistry, a limpid, colourless, inflammable liquid, of an agreeable ethereal odour and pungent taste.

Pyro-acid, in chemistry, an acid made by subjecting another acid to heat. Pyrochlore (Gr. pyr, and chloros greenish yellow), a reddish-brown or black mineral, consisting of titanic acid, lime, protoxide of uranium, peroxide of cerium, protoxide of manganese, peroxide of iron, peroxide of tin, and water sp. gr. 4.20; H = 5.

Pyrocitric, in chemistry, noting an acid obtained by distilling citric acid. Pyro-electric'ity, electricity developed by heat, as in certain crystals. Pyrolig'neous, Pyrolig'nous (Gr. and Lat.), noting an acid obtained from wood.

Pyrolignite (Gr.), a salt formed by the union of pyroligneous acid with a base. Pyrolith'ic (Gr.), noting an acid obtained from uric acid.

Pyrology (Gr.), a treatise on heat or fire.

Pyrolu'site (Gr. pyr, and louo to loosen), in mineralogy, common black manganese. It is the most important and most abundant of all the ores of manganese, and, according to Thomson, consists of binoxide of manganese, silica, and peroxide of iron: sp. gr. 4.97; H = 2-2.8.

Pyroma'lic Acid (Gr. pyr, and Lat. malum an apple), in chemistry, a volatile substance obtained by heating malic acid in close vessels.

Pyrom'etry (Gr. pyr, and metron a measure), the measurement of heat, or the expansion of bodies by heat.Pyrometer is an instrument for the measurement of expansion caused by heat.

Pyromorphite (Gr.), in mineralogy, native phosphate of lead. Pyromu'cous (Gr. pyr, and mucous), in chemistry, noting an acid obtained from sugar, gum, and mucilage.Pyromucite, a salt formed of pyromucous acid and a base.

Pyron'omy (Gr.), the laws of igneous action in chemical processes.

Pyrope (Gr.), in mineralogy, a fiery, brilliant red garnet, a gem highly prized.

Pyrophane (Gr. appearance of fire), a mineral said to change its colour by heat.

Pyroph'orus (Gr. bearing fire), a substance which spontaneously takes fire when exposed to air. Pyrophosphate (Gr.), in chemistry, a compound of pyrophosphoric acid with a base.

Pyrophosphoric (Gr.), in chemistry, an acid procured by exposing phosphoric acid to heat.

Pyrophyllite (Gr. pyr, phyllon a leaf, and lithos a stone), a foliated mineral of a light green colour. Pyrophy salite (Gr. pyr, and physa a bladder), in mineralogy, a variety of topaz.

Pyropneumatic (Gr.), noting a kind of lamp for producing instantaneous light by the action of inflammable air upon a metallic substance. Pyroscope (Gr. viewing the fire), an instrument for measuring the intensity of heat radiating from a fire. Pyrosid'erite (Gr. fire-steel), in mineralogy, a mineral composed of peroxide of iron and water. Pyro'sis (Gr. inflammation), in pathology, a burning redness in the face. Pyros'klerite (Gr. pyr, and skleros hard), an emerald-green mineral, consisting of silica, alumina, magnesia, protoxide of iron, oxide of chromium, and water.

Pyros'malite (Gr. pyr, osme smell, and lithos a stone), a native submuriate of iron.

Pyrosome (Gr.), in entomology, a sort of compound Ascidian, which is remark. able for emitting phosphoric light. Pyrotartar'ic, noting an acid obtained by distilling pure tartrate of potassa. Pyrotar'trate, in chemistry, a salt formed by pyrotartaric acid and a base.

Pyrotechny, or Pyrotechnics (Gr. pyr, and techne art), the art or science of managing fire, particularly as applied to the art of war, and more especially the making of ornamental fireworks for amusement.

Pyrotic (Gr.), in pathology, a caustic medicine.

Pyrou'ric (Gr.), in chemistry, noting an acid obtained from uric acid. Pyroxene (Gr.), in mineralogy, the augite; a crystallized mineral. Pyrox'yle (Gr. pyr, and xylon wood), a term embracing all explosive substances obtained by immersing vegetable fibre in nitric or sulphuric acid. -Pyroxylic, in chemistry, applied to a spirit produced by the destructive distillation of wood.-Pyroxyline, a substance found in pyroxylic spirit. Pyrrhite (Gr. pyrrhos flame-coloured), a mineral of a deep orange yellow, and vitreous lustre.

Pyrrhocoraci'næ, or Pyrrhuli'næ, in ornithology, a sub-family of conirostral birds, of the order Passeres and family Corvidæ; Choughs.

In mathematical problems Q.E.D. stands for quod erat demonstrandum, which was to be demonstrated; and, in chemistry, Q.S. stands for quantum sufficit.

Quadra (Lat. quatuor four), in architecture, a square moulding, border, or frame encompassing a bas-relief, &c.; a term applied to the plinth or lower member of the podium. A prefix to compound words, signifying four. Quadrangle (Lat.), a plane figure with four angles. In geometry, the fourth part of a circle; an arc of 90°.

Quadrant (Lat. the fourth part), a mathematical instrument for taking altitudes; an instrument used in gunnery for elevating and pointing cannon, &c. Quadrant of altitude is an appendix to an artificial globe, consisting of a slip of brass graduated into 90°, of the same length as those on one of the great circles of the globe, and used as a scale for measuring the distance between places in degrees.

Quadrat (Lat. quadratus squared), a mathematical instrument for measuring altitudes, called also a geometrical square and line of shadow.-In printing, a square piece of metal to fill up a void space between words and letters.

Quad'ratrix (Lat.), in geometry, a mechanical line, by means of which right lines are found equal to the circumferences of circles.

Quad'rature (Lat. quadratio act of squaring), in mathematics, the determination of the area of a curve.In astronomy, the position of the moon when she is 90o from the sun. -The quadrature of the circle is a problem of great celebrity in the history of mathematical science. In anatomy, quadratus lumborum, a muscle arising from the crest of the ilium. Quadratus femoris, a muscle arising from the tuber ischii.

Quad'ricorns (Lat. quatuor, and cornua horns), in entomology, a family of insects having four antennæ.-In zoology, a four-horned antelope.

Pyrrhotine (Gr.), a mineral composed chiefly of sulphur and iron. Pyul'con (Gr.), a surgical instrument for extracting pus from a cavity. Pyu'ria (Gr. pyon pus, and ouron urine), in pathology, evacuation of pus along with the urine.

Pyx (Gr. pyxis), a box used for the trial of gold and silver coin.

Quadrifurcate (Lat. quatuor, and furca a fork), doubly forked. Quadrino'mial (Lat. quatuor, and nomina names), in algebra, having four terms.

Quadripartite (Lat.), divided into four parts.

Quadrisul'cate (Lat.), in zoology, an unguiculate quadruped, having the hoof divided into four parts. Quadrox'alate, in chemistry, a salt composed of four equivalents of oxalic acid and one of base. Quadru'mana (Lat. four-handed), in zoology, the second order of mammiferous animals in Cuvier's system, as the Apes, Monkeys, &c. Quadrune, in mineralogy, a kind of grit-stone with a calcareous cement. Quaquaver'sal (Lat. quaquà and versus, inclined on every side), in geology, noting the dip of beds to all points of the compass around a centre, as in the case of beds of lava around the crater of a volcano.

Quartan (Lat. quartus fourth), in pathology, applied to a form of ague; occurring every fourth day.

Quarta'tion (Lat. art of quartering), in metallurgy, the separation of silver from gold by the agency of nitric acid. In chemistry, a process by which the quantity of one thing is made equal to the fourth part of another.

Quartersil'icate, a mineral in which four atoms of silica are combined with one atom of some other substance. Quartet (Ital.), in music, a piece arranged for four voices or four in

struments.

Quartz (Germ.), a transparent mineral, composed of pure silex; rock-crystal; one of the ingredients of granite, found under every variety of form: sp. gr. 2.5-2.7; H = 7'0. Quartzite (Germ.), in mineralogy, an aggregate of grains of quartz; quartz rock.

Quartz'sinter, in mineralogy, a substance found in the form of of siliceous concretions.

Quaver (Welsh), in music, a note or measure of time equal to half a crotchet, or the eighth of a semibreve. Quercitron (Fr.), the bark of an American oak, which furnishes an excellent yellow dye-stuff.-Quercitrine is the colouring principle of quercitron.

Queruli'ne (Lat.), in ornithology, a subfamily of dentirostral birds; order Passeres.

Queues d'Hironde [pron. kew'deronde], in fortification, lines composed of projecting tenailles, or works.

Quillai Bark, the bark of the Quillaia saponaria, used to make a lather instead of soap, when washing silks and woollens.

Quincite (Fr.), a mineral found in the limestone deposit in the neighbourhood of Quincey, in France. It consists of silica, magnesia, protoxide of iron, and water.

Quincunx (Lat. quinque five), an order or arrangement of five; a peculiar arrangement of anything in rows, as

trees.

Quindecagon (Lat. quindecim fifteen, and Gr.gonia an angle), in geometry, a plane figure of fifteen sides, and as many angles.

Quinine', or Quin'ine, an alkaline substance prepared from cinchona or yellow bark, much used in medicine as a tonic and febrifuge; Peruvian bark.

Quin'odine, a substance similar to quinine, extracted from the yellow bark.

Quinque- (Lat.), a prefix to many scientific words, denoting five; as, Quinquangular, having five angles;Quinquefid, five-cleft;-Quinquefoliated, having five leaves; -Quinquelobate, having five lobes, applied in botany to parts which are divided into five distinct lobes;-Quinquelocular, having five cells;-Quinquepartite, divided into five parts;-Quinquevalvular, having five valves.

Quinsy (Gr. kyon a dog, and ancho to strangle), in pathology, an acute inflammation of the tonsils.

Quintetto (Ital.), in music, a vocal or instrumental composition in five parts, in which each part is obligato, and performed by a single voice or instrument.

Quintile (Lat.), in astronomy, the aspect of planets when distant from each other the fifth of a circle.

Quiscali'næ, in ornithology, a subfamily of conirostral birds, of the order Passeres.

Quoin (Fr.), in architecture, a corner or angle of a building. In gunnery, a loose wedge placed below the breech of a cannon to adjust its elevation.In printing, a wedge used for fastening the type together.

Rabdol'ogy (Gr. rabdos a rod, and logos

a discourse), in arithmetic, a contrivance to facilitate the performance of multiplication and division by means of rods; called also Napier's bones. Ra'bies (Lat.), madness arising from

the bite of a rabid animal.

Raceme (Lat. racemus a cluster of grapes), in botany, a form of inflorescence in which the flowers are arranged along an axis.-Racemic, in chemistry, is an epithet denoting an acid found in the tartar obtained from certain vineyards. - Racemovinic acid is an acid formed by the action of alcohol on racemic acid.

Rachis (Gr. the spine), in botany, the axis of inflorescence; the petiole of a leaf. In zoology, the vertebral column of Mammals and birds.

Rachi'tis (Gr. rachis), in pathology, a disease affecting children; the rickets. Rack (Sax.), in mechanics, a straight bar of metal with cogs or teeth cut along its edge, by which it is moved up and down.

luminous point or object from which light emanates, that falls on a mirror or lens.

Radia'ta (Lat.), the fourth great division of the animal kingdom. The radiated animals are among the most frequent organic remains in the transition strata. These animals comprise all those which were formerly calied zoophytes, or animal-plants, as the Corallines, &c.

Ra'diated (Lat. issued in rays), in mineralogy, having crystals diverging from a centre. -Radiated pyrites is a variety of sulphuret of iron, occurring most commonly in coal-beds.

Rad'ical (Lat. radix a root), in chemistry, an epithet equivalent to base, but applied only to acids; chlorine being the simple radical of muriatic acid, and cyanogen and iron the compound radical of ferrocyanic acid. In algebra, a radical quantity is one affected by the radical sign.The radical sign, √, is that by which the root of a quantity is expressed: the particular root is indicated by a small figure placed to the left of this sign, which by itself denotes the square root;-3, 4, 5√, express the cubic root, the biquadrate, and the fifth roots, respectively.

Rad'icule (Fr.), in botany, that end of the embryo which is opposite to the cotyledons.

Ra'diolite (Lat. radius a little ray), in mineralogy, a variety of natrolite.

Radiom'eter (Lat. radius, and Gr. metron a measure), an instrument for taking altitudes.

Ra'dius, pl. Ra'dii (Lat.), in geometry, the semi-diameter of a circle. In the higher geometry, radius vector is a right line drawn from the centre of force in any curve in which a body is supposed to move by centripetal force, to that point in which the body is imagined to be. In anatomy, the radius is the small bone of the forearm. In fortification, a term applied to a line drawn from the centre of the polygon to the extremity of the exterior side, there being the exterior, the interior, and the right radius.

Radix, pl. Rad'ices (Lat.), in arithmetic, any number which is arbitrarily made the fundamental number of a system. In algebra, the root of a finite expression from which a series is

raised.

Ragstone, in mineralogy, a dark grey siliceous sandstone, which has an uneven fracture.

Ra'ide (Lat.), in ichthyology, a family of Flat-fishes; the Rays.

Railway, a way constructed of tracks of iron called rails, on which the wheels of the railway-carriages roll. -Railway-chairs are pieces of iron made to receive and support the rails, and which rest on the sleepers or blocks. Railway-sleepers are the underlying timbers to which the chairs are fixed.

Rainbow, in meteorology, the brilliantcoloured arch which is seen when rain is falling in the region of the sky opposite to the sun.

Rain Gauge, an instrument for measuring the quantity of rain that falls; a pluviameter.

Rake, in military science, to fire in the direction of the length of anything, particularly of a ship; to enfilade. Ral'lidæ, in ornithology, a family of birds, of the order Grallæ; the Rails. Ralphite, in mineralogy, a sort of fibrous hornblende.

Ram, in astronomy, the sign of the zodiac Aries, which the sun enters on

the 21st of March. In the arts, the ram's-horn is a kind of scroll ornament.

Ramen'ta (Lat. chips), in botany, soft, chaff-like hairs growing upon the petioles of ferns.

Ramollisse'ment (Fr. from Lat. mollis soft), in pathology, a softening of the brain, or other parts of the body. Rampant (Sax. rempend), a term of frequent use in heraldry, and applied to a lion or other beast when represented as standing on its hind legs. The lion rampant, as it betokens vigour and courage, is the most frequent of all bearings. When the lion stands upright on his hind legs, it is called rampant gardant, and rampant regardant when the beast looks behind. In architecture, rampant arch, an arch the abutments of which spring from an inclined plane. Rampart (Fr.), in fortification, an elevation or mound of earth round a place, capable of resisting the shot of an enemy, and formed into bastions, curtains, &c.

Ramphastidæ (Gr. ramphos a beak), in ornithology, a family of birds with enormous bills; the Toucans, of which the Ramphastos is the genus. Ramps (Fr.), in fortification, the slopes or ways leading from the inward area or lower part of a work to the rampart.

Ramus (Lat. a branch), in anatomy, the branch of an artery.-Ramus anastomaticus magnus is a branch of the brachial artery. Range, in nautology, a length of cable equal to the depth of water. In gunnery, the horizontal distance to which a shot or other projectile is carried. Ran'idæ (Lat. rana a frog), the family of batrachian reptiles, of which the Frog is the type.

Ranine (Lat. rana), in anatomy, applied to an artery of the tongue. Ran'ula (Lat. rana), in pathology, an inflammatory tumour under the tongue, arising from an accumulation of saliva and mucus. Ranunculaceæ (Lat.), in botany, a nat. order of Exogens, of which the Ranunculus, or Crow's-foot, is the type. Rapha'nia (Gr. raphanis the radish), in pathology, a disease attended with spasms of the joints, trembling, &c. Raphe (Gr. a seam), in botany, the vascular cord communicating between the nucleus of an ovule and the placenta. In anatomy, a line having the appearance of a seam, as that of the corpus callosum, &c. Raph'ides (Gr. raphis a needle), in botany, acicular and other crystals scattered in vegetable tissue.

Raph'ilite (Gr. raphis, and lithos a stone), a mineral occurring in diverging, acicular crystals; lustre glassy and silky; constituentssilica, lime, alumina, protoxide of iron, protoxide of manganese, magnesia, potash, and moisture: sp.gr.2.85; Η = 3.75.

Rapto'res (Lat. robbers, from rapio to snatch), in ornithology, an order of birds which live by rapine; birds of prey.

Rarefac'tion (Lat. rarus thin, and facio to make), state of being rarefied; applied specially to air and gales.

Raso'res (Lat. rasor a scraper, from rado to scratch), in ornithology, an order of birds, including the families Pavonidæ, Tetraonidæ, Strathonidæ, Columbidæ, and Megapodiidæ.

Ratafia (Fr. and Sp.), liquor compounded with alcohol, sugar, and the odoriferous or flavouring principles of vegetables.

Ratchet, in mechanical science, a piece of mechanism, one end of which abuts against a tooth of a wheel, called a ratchet-wheel.

Rath'ofite, in mineralogy, a species of garnet found in Sweden. Ra'tio (Lat.), in mathematics, the mutual relation which two magnitudes or quantities of the same kind bear to each other: thus, the ratio of 6 to 3 is or 2; and the ratio of 3 to 6 isor.-In arithmetic and algebra, a rational quantity is an expression in definite terms, or one in which no extraction of a root is left which

cannot be extracted by known processes: thus, 2, √9, 3√a6, are rational quantities, and √2, 3/9, 41/ab,

are irrational or surd quantities.-In geography, rational horizon is the plane passing through the centre of the earth parallel to the sensible horizon of the place to which it is referred.

Ratlines, or Ratlins, in nautology, small horizontal lines extending over the shrouds, forming the steps of ladders. Rauchwacke (Germ.), in geology, one of the calcareous members of the Zechstein formation.

Ravelin (Fr.), in fortification, a detached work, composed of two embankments. In this it differs from a half-moon, which is placed before an angle. Ray'onnant (Fr.), in heraldry, darting forth rays.

Razee (Fr.), in nautology, a ship-of-war cut down to an inferior class.

Re-, or Red-, a Lat. preposition used in compound words, signifying repeti

Reaction (Lat. re, and ago to act), in dynamics, the resistance made by a body to the action or impulse of another body.

Rea'gent (Lat.), in chemistry, a substance used to detect the presence of other bodies.

Real'gar, a mineral occurring in splendid translucent crystals of a brilliant red colour, consisting of arsenic and sulphur; it is a protosulphuret of arsenic: sp. gr. 3.3-3.6. Realgar is also artificially prepared and used as a pigment.

Reaumuria'ceae (in honour of M. Réaumur), in botany, a nat. order of exogenous plants, of which Reaumuria is the type.

Reciprocal Ra'tio, in arithmetic and algebra, is that between the reciprocal of two quantities. In geometry, reciprocal figures are two figures of the same kind, so related that two sides of the one form the extremes of an analogy, of which the means are the two corresponding sides of the other.

Reciprocating Motion, in mechanical science, a form of action illustrated in the suspension of a rigid bar on an axis.

Reclina'tion (Lat. re, and clino to lean), in surgery, an operation for the cure of cataract.

Rectangle (Lat. rectus right, and'angulus angle), any geometrical figure containing one or more right angles; a right-angled parallelogram. -Rectangular, having one or more angles of 90°.

Rectification (Lat.), in chemistry, the purification of any substance by repeated distillation.

a

Rectilinear (Lat.), in geometry, figure whose boundaries are right lines.

Rectum (Lat. rectus), in anatomy, the last portion of the large intestines (the straight gut), terminating in the

anus.

Rectus (Lat. straight), in anatomy, an epithet applied to several straightformed muscles of the body.-Rectus capitis is the name of five muscles arising from the upper cervical vertebræ, and inserted into the occipital bone; these are the R. capitis anticus major; the R. capitis anticus minor; the R. capitis lateralis; the R. capitis prosticus major; and the R. capitis prosticus minor. - The muscles connected with the eye are, the R. superior, which raises the eye; the R. inferior, which depresses it; the R. internus, which draws it inwards; and the R. externus, which draws it outwards. The Rectus ab