Part 24

Bobbinite: the only gunpowder explosive allowed in England, not allowed in foreign mines; alkali nitrate, carbohydrates, wax may be added. Shatters coal less than high explosives.

Cambrite: a Nobel carbonite plus 8 per cent of a cooling agent.

Denaby Powder: ammonium nitrate, alkali nitrate, T.N.T., ammonium chloride.

Dynobel: nitroglycerine 15, collodion cotton 0.5, nitro-body 3, ammonium nitrate 46, wood-meal 5.5, salt 29.5, magnesium carbonate 0.5. Limit charge, 18 to 30 ounces. Swing of ballistic pendulum, 2.35 inches.

Monarkite: ammonium and sodium nitrate, nitroglycerine, nitrocotton, starch, mineral jelly, salt.

Monobel: ammonium nitrate, nitroglycerine, wood-meal, salt, alkali chloride, magnesium carbonate; nitro-body may be present.

Negro Powder: Grisounite type; ammonium nitrate 88, T.N.T. 10, graphite 2.

Rex Powder: nitroglycerine 12, salt 20, wood-meal 8, ammonium nitrate 60. Charge, 20 ounces. Swing of pendulum, 2.61 inches.

Rippite (Super): nitroglycerine, nitrocotton, potassium nitrate, borax, alkali chloride.

Roburite: ammonium nitrate 61, T.N.T. 16, salt 23.

Stomonal: nitroglycerine, ammonium nitrate, sodium nitrate, wood-meal, wheat-flour, salt, ammonium oxalate.

Thames Powder. Similar to above.

_Danish._

Aerolite: ammonium nitrate 78.1 per cent, potassium nitrate 7.5 per cent, sulphur 8.75 per cent, tar 2.5 per cent, sago-meal 1.25 per cent, manganese dioxide 1.25 per cent, resin 0.6 per cent.

Poudre Blanche Cornil: ammonium nitrate, alkali nitrate, nitronaphthalene, lead chromate.

_French._

Favier Explosives. See under _Belgian_ explosives.

Grisounite. As above.

Grisoutine or Grisou Dynamite. It is a mixture of ammonium nitrate and blasting gelatine. It is the only explosive except Grisounite allowed in the more dangerous French mines.

Naphthalite (Grisou): potassium chlorate 80 per cent, aryl hydrocarbons, 12 per cent nitrocompounds not trinitro-bodies, paraffin, fatty oils, flour and other organic substances. May contain alkali chlorides and up to 4 per cent blasting gelatine.

_German._

Albit (Wetter): a chlorate explosive replacing nitrates; scarce during the war.

Astralit (Wetter): ammonium nitrate explosive containing some blasting gelatine. Many varieties, which may also contain rape-oil and potato-meal. Has been used in trench howitzers.

Carbonit. Numerous compositions come under this name and are made in different countries. Consists chiefly of nitroglycerine and metallic nitrates. Arctic carbonite, a low-freezing mixture, contains 15.5 per cent nitroglycerine, 10.5 per cent nitrohydrocarbon, 42 per cent potassium nitrate, 31.7 per cent wood-meal, and 0.3 per cent calcium carbonate.

Chloratzit: potassium chlorate or perchlorate, aryl nitro-bodies, resins, and carbohydrates. For coal-mines add cooling agents.

Detonit: ammonium nitrate, charcoal, meal, 4 per cent blasting gelatine, neutral salts.

Donarit: ammonium nitrate 80 per cent, trinitrotoluene 12 per cent, rye-flour 4 per cent, nitroglycerine 4 per cent. The standard in Germany for sensitiveness of ammonium nitrate explosives.

Dorfit: ammonium nitrate, trinitrotoluene, flour, salt, alkali nitrate.

Dynamit: nitroglycerine 75 per cent, Kieselguhr 25 per cent.

Gehlingerit: ammonium nitrate, trinitrotoluene, flour.

Permonit: a perchlorate explosive.

Tremonit: contains gelatinized dinitroglycerine, pea-flour, and salt.

SOME BLASTING EXPLOSIVES

Ammonal: ammonium nitrate 80 to 90 per cent, aluminium 4 to 18 per cent, charcoal 2 to 6 per cent. The more violent mixtures contain some trinitrotoluene in addition. Has been used in grenades and by Austrians in trench-howitzer bombs. Not suitable in underground workings owing to poisonous gases evolved.

Astralit: a mixture of ammonium nitrate and blasting gelatine. May contain wood-meal, trinitrotoluene, paraffin-oil. Has been used for projectiles.

Carbodynamite: nitroglycerine absorbed in cork charcoal instead of guhr.

Gelignite: nitroglycerine 56 to 63 per cent, nitrocotton 4 per cent, wood-meal 7 per cent, potassium nitrate 27 per cent, calcium carbonate 0.2 per cent.

Oxyliquit: liquid oxygen absorbed in a porous combustible material. Used in construction of Simplon Tunnel. Very cheap; safe after misfire because oxygen evaporates off.

Perdit: German mining, demolition, and rifle grenade explosive. Ammonium nitrate 76 per cent, potassium perchlorate 6 per cent, wood-meal 2 per cent, dinitrotoluene 16 per cent.

Rendarock: a brand of American dynamite.

Sprengel Explosives: one or both of the substances to be liquid, and mixing to occur shortly before firing. Nitric acid, alkali chloride, nitrogen peroxide on nitrobenzene, nitronaphthalene, carbon bisulphide, petrol, picric acid. Panclastite, Promethee, Rack-a-Rock, are examples of this class.

Tonite: gun-cotton and barium nitrate.

SOME HIGH EXPLOSIVES

Alumtol: ammonium nitrate, trinitrotoluene, aluminium powder. Used for trench mortars, bombs, &c.

Amatol: a mixture of ammonium nitrate and trinitrotoluene, used for shell-filling. Called by Germans Fuellpulver. The Germans did not develop this explosive as much as the Entente Powers, who effected great economy of trinitrotoluene.

Blastine: ammonium perchlorate, sodium nitrate, dinitrotoluene, paraffin-wax. It evolves hydrochloric acid gas.

Blasting gelatine contains 93 per cent nitroglycerine and 7 per cent nitrocotton. It is the most powerful explosive in common use.

Cresylite is a French explosive, and contains picric acid and nitrated cresol.

Fumyl is a smoke-producing explosive, and contains trinitrotoluene and ammonium chloride. It was used to open poison-gas shells.

Granatfuelling (Shell Filling): a term used by the Germans.

Granatfuelling C/84 is picric acid.

Granatfuelling C/02 is trinitrotoluene.

Other substances were used by them for shell filling, such as trinitroanisole, dinitrobenzene, hexanitrodiphenylamine, and hexanitrophenylsulphide.

Lyddite: a term for picric acid formerly used in shells.

T.N.T. is trinitrotoluene or trotyl.

Toxol is a mixture of trinitrotoluene and trinitroxylene.

Triplastite is a plastic high explosive containing 70 per cent nitrotoluenes, 8 per cent nitrocotton, 29 per cent lead nitrate. Used for shell filling.

SOME MISCELLANEOUS EXPLOSIVES

Anilite: Sprengel type. French liquid explosive used in aerial bombs.

Centralite: not an explosive but a stabilizer and regulator. It is dimethyldiphenylurea.

Collodion Cotton: low nitralion nitrocotton, soluble in a mixture of ether and alcohol. It dissolves in nitroglycerine and liquid nitro-body, preventing their exudation.

Gelatine Dynamite: a mixture of blasting gelatine with potassium nitrate and wood-meal. It may also contain calcium and magnesium carbonate and mineral jelly.

Gelignite is similar to Gelatine Dynamite, but contains less Blasting Gelatine.

Halakite: contains potassium chlorate, ammonium nitrate, trinitrotoluene or other nitro-body; may contain nitrocotton, sodium nitrate, and wood-meal.

Pyrocollodion: highly nitrated, soluble gun-cotton. Adopted by the United States.

White Gunpowder: a mixture of potassium chlorate, potassium ferrocyanide, and sugar. Very sensitve, and only used in the laboratory.

PROPELLANTS FOR SHOT-GUNS

Amberite: insoluble nitrocotton 18.6 per cent, nitrates 28 per cent, soluble nitrocotton 46 per cent, vaseline 6 per cent.

Du Pont Smokeless Powder: nitroglycerine 10 per cent, ammonium nitrate 67.5 per cent, wood-pulp 8 per cent, salt 15 per cent (for coal-mines). Soluble nitrocotton 46 per cent, metallic nitrates 2.2 per cent (for shot-guns).

E.C. Powder: insoluble nitrocotton 44 per cent to 48 per cent (Empire Powder), soluble nitrocotton 30 per cent to 34 per cent, metallic nitrates 14 per cent to 9 per cent, vaseline 6 per cent to 7 per cent, camphor 4.6 per cent.

Ideal Powder: made by Nobels.

Neonite. Similar to the above compositions, but containing 73 per cent of insoluble nitrocotton, 9 per cent soluble nitrocotton. It is also made for rifled small-arms especially for rim-fire rifles.

New Explosives Company Smokeless Powder. Similar to above.

Rifleite: insoluble nitrocotton 1.7 per cent, soluble nitrocotton 82.5 per cent, nitro-body 4.8 per cent. The nitrocellulose is made from curcuma.

Ruby Powder: a cheap non-solvent powder, 46 per cent insoluble nitrocotton, 4 per cent soluble nitrocotton.

Smokeless Diamond and Stoumarkel Smokeless are similar to above.

PROPELLANTS FOR RIFLED FIRE-ARMS

Amide Powder: ammonium nitrate, potassium nitrate, charcoal. Has also been used in German artillery.

Ammonpulver: ammonium nitrate and charcoal. Has been used by Austrian artillery, and lately reintroduced by the Germans.

Ballistite: equal parts of nitroglycerine and soluble nitrocotton with some mineral jelly.

Cordite: the principal smokeless powder of the British Empire.

Indurite: gun-cotton and nitrobenzene. Abandoned by U.S. navy.

Neonite: a gelatinized powder. Contains nitrocellulose insoluble and soluble, metallic nitrates, and vaseline.

Noddite: a strip sporting-rifle powder containing nitroglycerine, nitrocellulose, mineral jelly.

Rottweil Smokeless Powder: a gelatined powder containing camphor and diphenylamine.

See also _Grenade_; _Shell_; _Torpedo_; _Fireworks_; _Rockets_.

EXPO'NENT. In algebra a^3 denotes three a's multiplied together; a^n means that n of the letter a are to be multiplied. These numbers or letters placed immediately above and to the right of another number or letter are called exponents, and indicate the power to which the number or letter is raised. Exponents can be fractional or negative, in which case new interpretations can be found. On the assumption that a^m x a^n = a^{m+n} for all values of m and n, a^{1/n} is interpreted as the nth root of a, a^{-n} as the reciprocal of a^n.

EXPONENTIAL THEOREM. If a^x = N, x is said to be the logarithm of N to the base a. There are two bases of logarithms in common use, the base 10 and the Napierian base e. The exponential theorem states that the value of e^x is given by the infinite series 1 + x + x^2/(1.2) + x^3/(1.2.3) + ... + x^n/(1.2.3..n) +, &c. Putting x equal to 1, e = 1 + 1 + 1/(1.2) + 1/(1.2.3) + 1/(1.2.3.4) +, &c. e can be expressed to any number of decimal places by working out the value of the terms on the right-hand side. It is an incommensurable number which to five decimal places is equal to 2.71828. See _Logarithm_.

EXPORTS. See _Foreign Trade_.

EX POST FACTO, in law, a term designating something as done after and bearing upon something previously done; thus a law is said to be _ex post facto_, or retrospective, when it is enacted to punish an offence committed before the passing of the law.

EXPOSURE, the situation of a building, &c., with respect to sun and wind; 'aspect' with regard to the quarter of the heavens. A house facing south-west or south-east will be found much healthier than one facing due north; and as it is also warmer, less fuel will be required for heating purposes.

EXPRESSED OILS, in chemistry, are those which are obtainable from bodies only by pressing, to distinguish them from mineral and essential oils, which last are, for the most part, obtained by distillation.

EXTENSION, (1) in physics and metaphysics, that property of a body in virtue of which it occupies a portion of space. (2) In logic, _extension_ is the extent of the application of a general term, that is, the objects collectively which are included under it; thus, the word figure is more extensive than triangle, circle, or parallelogram; European more extensive than French, Frenchman, German, &c. Matter and mind are the most extensive terms of which any definite conception can be formed. Extension is contrasted with _comprehension_ or _intension_.--Cf. Titchner, _Text-Book of Psychology_.

EXTINCTEUR (eks-tan-t_eu_r), an apparatus for the extinction of fire, consisting of a metallic case containing water and materials for generating carbonic acid. When required, the materials are brought into contact by pushing a rod which breaks a bottle containing acid, the gas mixes with the water, and the pressure generated is sufficient to project the water charged with the gas to a distance of 40 or 50 feet.

EX'TRACT, a term to denote all that can be dissolved out of a substance by a specified menstruum, such as water, alcohol, ether, &c. In modern pharmacy the term is applied to two kinds of preparation from vegetables. One is got by digesting the plant in water or other solvent, and evaporating or distilling away the excess of solvent until the extracted matter is sufficiently inspissated. The other is got by bruising the plant in a mortar, separating the juice, warming it until the green colouring-matter separates, and filtering it off. The juice is next heated until the albumen coagulates, and again filtered. The juice is now evaporated to a syrup, the green colouring-matter added and well mixed, and the evaporation is thereafter continued until the required concentration is attained. Extracts must be capable of being redissolved, so as to form a solution like that from which they were derived. Extracts are used in cookery, medicine, and the manufacture of perfumery.--_Extract of Meat_ (_extractum carnis_) is a soft, yellowish-brown solid, or very thick syrup, which is employed as a portable soup. It is now manufactured on the large scale by processes proposed by Liebig.

EXTRADI'TION (Lat. _ex_, out, and _tradere_, to hand over), the act by which a person accused of a crime is given up by the Government in whose territories he has taken refuge to the Government of which he is a subject. Conventions have been entered into by Britain with almost all civilized countries for the apprehension and extradition of persons charged with particular offences, especially those of the most heinous stamp, such as murder, robbery, embezzlement, arson, rape, and piracy. The Extradition Act of 1870 makes special provision that no criminal shall be surrendered for a political offence, and that the criminal shall not be tried for any but the crime for which he was demanded. Other British Extradition Acts are those of 1873, 1895, and 1906. See _International Law_.--Cf. Sir E. Clarke, _The Law of Extradition_.

EXTRAVAGAN'ZA, in music or the drama, a species of composition designed to produce effect by its wild irregularity and incoherence; differing from a burlesque in being an original composition and not a mere travesty.

EXTRAVASA'TION (Lat. _extra_, beyond, and _vas_, vessel), an escape of some fluid, as blood or urine, from the vessel containing it. _Blood extravasation_, in contusions and other accidents, is when blood-vessels are ruptured by the injury, and the blood finds its way into the neighbouring tissues. In some accidents to the urethra and bladder extravasation of urine is a very serious occurrence.

EXTREME UNCTION has been, since an early period, one of the seven sacraments of the Roman Catholic Church. It is performed in cases of mortal disease by anointing in the form of a cross, the eyes, ears, nose, mouth, hands, feet, and reins (in the case of males). It is administered after confession and the eucharist, and is believed to remove the last stains of sin. It can only be administered by a bishop or priest, and is not applied in the case of young children or excommunicated persons.

EXU'MA, GREAT and LITTLE, two of the Bahama Islands. The former is 30 miles long and 3 miles wide, and has a good harbour. Pop. 3465.

EYALET ([=i]'a-let), a former administrative division of the Turkish Empire, subdivided into sanjaks or provinces, and kazas or districts. It was ruled by a pasha, and gave place to the vilayet on the reorganization of the empire in 1871.

EYCK ([=i]k), Hubert and Jan van, brothers, famous painters of the old Flemish school, born at Maaseyck, Hubert in 1366, Jan probably about 1385. They lived first at Bruges, whence the younger brother is called John of Bruges, and afterwards at Ghent, to which they removed about 1420. Here they executed the celebrated _Adoration of the Lamb_ for the Cathedral of Ghent; a painting which, in its different parts, contains above three hundred figures, and is a masterpiece. It was in two horizontal divisions, comprising ten panels, of which only the two central ones remain at Ghent, the others being at Berlin. Hubert did not live to see it completed. He died at Ghent (1426), as did also his sister Margaret, who was likewise a painter (1431). Jan finished the work in 1432, and returned to Bruges, where he remained till his death, which took place in 1441, and executed several excellent pieces. His reputation became very great even during his lifetime, by his share in the introduction of oil-painting; the original invention of which has been incorrectly ascribed to him by many. Jan van Eyck also introduced improvements in linear and aerial perspective, and in painting upon glass. Three portraits by Jan van Eyck, _The Scholar_, _The Man with a Turban_, and _Giovanni Arnolfini and his Wife_, are in the National Gallery, London; the _Madonna of the Chancellor Rollin_ is in the Louvre.--Cf. W. H. J. Weale, _John and Hubert van Eyck_.

EYE, the organ of vision, is an instrument presenting some analogy to a photographic camera. It is provided with a lens for focussing images upon a sensitive membrane called the _retina_. The walls of the globe of the eye are formed principally of two fibrous membranes: one white and opaque--the _sclerotic_ (Gr. _skl[=e]ros_, hard)--which envelops two-thirds of the globe posteriorly; and the other transparent, and resembling a horny plate, whence its name, _cornea_ (Lat. _corneus_, horny). The sclerotic is a tough fibrous coat, and is the part to which the phrase 'white of the eye' is applied. In the front of the globe the sclerotic is abruptly transformed into the transparent portion (the cornea), which is circular, and which forms a window through which one can see into the interior. A membrane, the _conjunctiva_, so named because it unites the eye to the lid, spreads over the anterior portion of the globe, and then folds back on itself and lines the internal surface of the eyelids. On the internal surface of the sclerotic is a vascular membrane called the _choroid_. This is essentially the blood-vessel coat of the eyeball. About the place where the sclerotic passes into the cornea the choroid becomes continuous with the _iris_, a round curtain, the structure seen through the cornea, differently coloured in different individuals. In its centre is a round hole, the _pupil_, which appears as if it were a black spot. The _iris_ forms a diaphragm suspended in the space behind the cornea which is filled with clear fluid, the _aqueous humour_. The _iris_ consists of a framework of connective tissue, and its posterior surface is lined by cells containing pigment which gives the colour to the eye. In its substance are bundles of involuntary muscular fibres, arranged in a ring round the margin of the pupil. In a bright light the circular fibres contract and the pupil is made smaller; but in the dark these fibres relax and allow the pupil to dilate more or less widely, thus allowing more luminous rays to enter the eye. Just behind the pupil is the _crystalline lens_, resembling a small, very strongly magnifying glass, convex on each side, though more so behind. Minute bands of muscle in the choroid can alter the convexity of the lens, and thus adapt its focus to the position of objects at different distances. The large space in the globe of the eye that intervenes between the retina lining its inner surface and the lens in front is occupied by a transparent jelly-like mass called the _vitreous body_. The internal surface of the choroid, or rather the pigmentary layer which covers it, is lined by the retina or nervous tunic upon which the images of the objects that we see are focussed. The retina is a very complex mechanism consisting of certain elements which are stimulated by light, and others that transmit the effects of such stimulation as a nervous current to the optic nerve which carries it to the brain. It is composed of cones and cylinders or _rods_, joined together like the stakes of a palisade, perpendicular to the plane of the membrane, and forming by their free extremities a mosaic, each microscopic division of which is about 0.0008 of a line in diameter according to Helmholtz, and represents a section of a rod. These rods and cones are believed to be the agents by whose aid the waves of light become transformed into the stimulus of a sensation. The ocular globe is put in motion in the orbit by six muscles, grouped two by two, which raise or lower the eye, turn it inward or outward, or on its antero-posterior axis. In these movements the centre of the globe is immovable, and the eye moves round its transverse and vertical diameters. These three orders of movements are independent of each other, and may be made singly or in combination, in such a manner as to direct the pupil towards all points of the circumference of the orbit. Each eye is furnished with two eyelids, moved by muscles, which shield it from too much light and keep it from being injured. They are fringed with short, fine hairs called eyelashes; and along the edge of the lids is a row of glands similar to the sebaceous glands of the skin. The eyebrows, ridges of thickened integument and muscle, situated on the upper circumference of the orbit and covered with short hairs, also regulate to some extent the admission of light by muscular contraction. In reptiles, some fishes (sharks, &c.), in birds, and in some mammals a third eyelid or nictitating membrane is present, and can be drawn over the surface of the eye so as to clear it of foreign matters, and also to modify the light. The lachrymal apparatus is composed of, firstly, the _lachrymal gland_, which lies in a depression of the orbital arch; secondly, the _lachrymal canals_, by which the tears are poured out upon the conjunctiva a little above the border of the upper lid; thirdly, the _lachrymal ducts_, which are destined to receive the tears after they have bathed the eye, and of which the orifices or _lachrymal points_ are seen near the internal ends of the lids; fourthly, the _lachrymal sac_, in which the lachrymal ducts terminate, that empties the tears into the _nasal canal_. The tears, by running over the surface of the conjunctiva, render it supple and facilitate the movements of the globe and eyelids by lessening the friction. The influence of moral or physical causes increases their secretion, and when the lachrymal ducts do not suffice to carry them off they run over the lids.