5. Moisture and Absorption of Moisture.—The amount of water contained in gunpowder is found by drying a carefully-weighed sample in a water oven f:>r a certain period ; from the weight lost, when allowed to cool out of contact with the air before weighing, the percentage of moisture can be calculated. The hygroscopic test consists in exposing a dried sample in a box, kept at a uniform temperature, to an atmosphere artificially saturated with moisture, and ascertaining the increase of weight in a certain time.
6. Firing Proof.—The nature of this will depend upon the purpose for which the powder is intended. For sporting powders, it will consist in the " pattern " given by the shot upon a target at a given distance, or, if fired with a bullet, upon the " figure of merit," or mean radial deviation of a certain number of rounds; also upon the penetration it effects through boards. For military purposes the powder is now always fired from the rifle or piece of ordnance with which it is to be used, and the initial or " muzzle " velocity ascertained by the Le Boulenge electric chronograph (see Gunnery), which measures the exact time the bullet or other projectile takes to traverse a known distance between two wire screens. By means of the "crusher gauges" alveady referred to, the exact pressure per square inch upon certain points in the interior of the bore can be found ; the maximum pressure can be considerably modified by increasing the cubic air-space given to the charge in the powder chamber. The figure of merit is also taken for siinall-arm powder.
All gunpowder made by or for the British Government is subjected to very strict limits of specification upon all the above-named points.
Bibliography.—Vanucchio Biringuccio, De la Pirotcchnia, Venice, 1540; Tartaglia, Quesiti c invenzioni divcrsi (lib. iii.), Venice, 1546; Peter Whitehorne, How tom r <ke Saltpetre, Gounpowdcr,kc., London, 1573; Nic. Macchiavelli, The Arte of Warre, transl. by Whitehome, London, 1588; Hanzelet, Rccucil de plusicrs Machines Militaires, Paris, 1620; Boillet Langrois, Modclles artifices defeu, 1620; Kruger, Chemical Meditations on the Explosion of Gunpowder (in Latin), 1636 ; Collado, On the Invention of Gunpowder (Spanish), 1641 ; The True Way to make all Sorts ofGunpoxuder and Matches, 1647; Hawksbee, On Gunpowder, 1686; Winter, On Gunpowder (iu Latin); Robins, New Principles of Gunnery, London, 1742 (new ed. by Hutton, 1805); Stahls, On the Nature and Utility of Saltpetre (German), Leipsie, 1748; D Antoni, Essame della Pohere, Turin, 1765 (transl. by Capt. Thomson, R.A., London, 1787); Count Rum- ford, "Experiments on Fired Gunpowder," Phil Trans. Roy. Soc., 1797; Cossigny, Rccherchcs phisiques et cheiniqucs sur la fabrication de la poudre a canon, Paris, 1807; Botteeet Rill ault, Traite de I art defabriqucr la poudre a canon, Paris, 1811 ; Eenaud, Instructions sur la fabrication de la Poudre, approuvees par le Ministrc de la Guerre, Paris, 1811; Hutton, Mathematical Tracts (vol. iii.)> 1812; Sir W. Congreve, A Short Account of Improvements in Gunpou-dcr made by, London, 1818 ; Fraxno, Tratado de la Teoria y Fabrica- cion de la Polvora en General, Segovia, 1817; Coleman, "On the Manufacture and Constituent Parts of Gunpowder," Phil. Mag., vol. ix. ; Braddock, Memoir on Gunpowder, London, 1832; Col. Oinodei, Dell origine dclla polvcre da gucrra, Turin, 1834 ; Proust, Memoircs sur la poudre a canon, Paris; Timmerhaus, Descriptions des divers procedes de la fabrication de la poudre a canon, Paris, 1839 ; Wilk inson, Engines of War, including the Maimfadure of Gunpowder, London, 1841 ; Major Mordecai, Experiments with Gu?i})owdcr in Washington Arsenal in the years 1843-4, Washington, 1845 ; La Cabane, De la poudre a canon ct de son introduction en France, Paris, 1845; Reinaud et Fave, Du feu Gregois et des origincs de la poudre a canon, Paris, 1845; Bunsen and Schiskoff, "On the Chemical Theory of Gunpowder," Pogyeiidorjf s Annalen, vol. cii. , 1857 ; Scoffern, Projectile Weapons of War and Explosive Com pounds, London, 1858; Gen. Piobert, Traite d Artillerie, Proprie tes et Effets de la Poudre, Paris, 1859; Gen. Rodman, Experiments on Metal for Cannon, and Qualities of Cannon Powder, Boston, 1861 ; Xapoleon III., Etudes sur le passt et I arcnir de V Artillerie, vol. iii., Paris, 1862; Anderson and Parlby, On the Manufacture of Gunpowder at Ishajwrc, London, 1862; Von Karolyi, "On the Products of the Combustion of Gun Cotton and Gunpowder," Phil. Mag., Oct. 1863; Count de St Robert, Traite de Thermodynamique, Turin, 1865 ; Capt. F. M. Smith, Handbook of the Manufacture and Proof of Gunpowder at WaltJiam Abbey, London, 1870; Berthollet, Sur la force de la Poudre, Paris, 1872; Sarrau, Effets de la Poudre et des Substances Explosives, Paris, 1874; Noble and Abel, Fired Gunpowder, London, 1875 ; C. L. Bloxam, Chemistry (art, "Gun powder"), 3d ed., London, 1875; Notes on Gunpowder and Gun Cotton, published by order of the Secretary of State for War, London, 1878.
(w. h. w.)
GUNPOWDER PLOT. See Fawkes.
GÜNS (Hungarian, Kuszeg), the second town in import ance of the Hungarian rnegye or county of Vas (Eisenburg), near the Styrian frontier, is favourably situated on the Gyongyos, 47 23 N. kt, 16 3V E. long. It is the see of a bishop, and from 1648 until the recent administrative changes of 1876 was a royal free town. Among the more noteworthy buildings are the cathedral, episcopal palace, a seminary for priests, a gymnasium, the county-hall, a hospital, three monastic houses, a museum of Roman anti quities, a house of correction, and several manufactories of cloth and of earthenware. The agricultural products of the neighbourhood consist principally of fruit and wine ; the trade in the latter especially is considerable. In 1870 the number of inhabitants was 6916, mostly of German extrac tion. The heroic defence of the fortress of Giins by Nicolas Jurisics against the army of Sultan Soliman, in August 1532, has given the town a special historical interest. In 1621 it suffered from the attacks of Gabriel Bethlen s troops, and in 1705 the suburbs were plundered and burnt by the forces of Francis Rak6czy. In 1729 and 1777 the town suffered much from fire, and in 1813, 1814, and 1821 from floods. The Eszterhazy family long held valuable possessions in the neighbourhood, and one of their castles still stands at the northern end of the town.
GUNTER, Edmund (1581–1626), was of Welsh extraction, but was born in Hertfordshire in 1581. He was educated on the royal foundation at Westminster school, and in 1599 was elected a student of Christ Church, Oxford. After graduating bachelor and master of arts at the regular times. he took orders, became a preacher in 1614, and in Novem ber 1615 proceeded to the degree of bachelor in divinity. Mathematics, however, which had been his favourite study in youth, continued to engross his attention, and on 6th March 1619 he was appointed to the professorship of astronomy in Gresham College, London. This post he held till his death, which took place on 10th December 1G26. With Gunter s name are associated several useful invention?, descriptions of which are given in his treatises on the Sector, Cross-staff, Bow, Quadrant, and other Instruments. He had contrived his sector about the year 1606, and written a description of it in Latin. Many copies were transcribed and dispersed, but it was more than sixteen years afterwards ere he allowed the book to appear in English. In 1620 he published his Canon Triangulorum, a table of logarithmic sines and tangents (extended to 7 decimal places) for every degree and minute of the quadrant. In later editions an account of the general use of the canon is prefixed, and Briggs s logarithms of the first 1000 numbers are appended. There is reason to believe that Gunterwas the first to discover (in 1622 or 1625) that the magnetic needle does not retain the same declination in the same place at all times. By desire of James I. he published in 1624 The Description and Use of His Majestie s Dials in Whitehall Garden, the only one of his works which has not been reprinted. He introduced the words co-sine and co-tangent for sine and tangent of the complement, and he suggested to Briggs, his friend and colleague, the use of the arithmetical complement (see Briggs s Arithmttica Loyarithmica, cap. xv.). His practical inventions are briefly noticed below.
