Page:Encyclopædia Britannica, Ninth Edition, v. 14.djvu/397

 L E A L E A 379 lead, buried in horse-dung or spent tanner s bark, and left to them selves for a considerable time. The organic bath, through its fer mentation, keeps up a suitable temperature and a constant supply of carbonic acid. By the conjoint action of the acetic acid and atmospheric oxygen, the lead is converted superficially into a basic acetate, which is at once decomposed by the carbonic acid, with for mation of white lead and acetic acid, which latter then acts dc novo. After a month or so the plates are converted to a more or less con siderable depth into crusts of white lead. These are knocked off, ground up with water, freed from metal-particles by elutriation, and the paste of white lead is allowed to set and dry in small coni cal forms. The coherent, snow-white cones are sent out into commerce. The German method differs from the Dutch in this that the lead is suspended in a large chamber heated by ordinary means, and there exposed to the simultaneous action of vapour of aqueous acetic acid and of carbonic acid. In the famous works at Klagenfurth and in the Lavantthal, Carinthia, the carbonic acid is produced by the fermentation of apple-must or infusion of raisins kept in tubs below the chambers. The inferior varieties of com mercial &quot; white lead&quot; are produced by mixing the genuine article with more or less of finely powdered heavy spar or occasionally zinc- white (ZnO), which latter, we may state in passing, is the most important of the relatively non-poisonous substitutes for white lead. The chloride, PbCl 2, is obtained by adding hydrochloric acid to a solution of lead salt, as a white precipitate, little soluble in cold water, less so in dilute hydrochloric acid, more so in the strong acid, and readily soluble in hot water, from which, on cooling, the excess of dissolved salt separates out in acicular crystals. A basic chloride Pb,&amp;lt; KJLj was introduced by Pattinson as a substitute for white lead. Powdered galena is dissolved in hot muriatic acid (PbS + 2HCl = PbCl.j -f- ILjS), the solution allowed to cool, and the deposit of impure chloride of lead washed with cold water to remove iron and copper. The residue is then dissolved in hot water, the dregs arc filtered off, and the clear solution is mixed with very thin milk of lime so adjusted that it takes out one-half of the chlorine of the PbCl 2. The oxychloride comes down as an amorphous white precipitate. Another oxychloride, PbCl 2 .7PbO, known as &quot;Cassel yellow,&quot; is produced by fusing pure oxide, PbO, with ^th of its weight of sal- ammoniac. The sulphate, PbS0 4, is obtained, by addition of sulphuric acid to solutions of lead salts, as a white precipitate almost insoluble in water, less soluble still in dilute sulphuric acid, insoluble in alcohol. Sulphide of ammonium blackens it, and it is soluble in solution of alkaline acetate of ammonia, which distinguishes it from sulphate of baryta. It is often obtained industrially as a bye-product. The chromate, PbOCr0 3, is prepared industrially as a yellow pig ment, by precipitating sugar of lead solution with bichromate of potash. The beautiful yellow precipitate is little soluble in dilute nitric acid, but soluble in caustic potash ley. The vermilion-like pigment which occurs in commerce as &quot;chrome-red&quot; is a basic chromate, prepared by treating recently precipitated normal chromate with a properly adjusted proportion of caustic soda, or by boiling it with normal (yellow) chromate of potash. The approxi mate composition is Cr0 3 .2PbO. The identification of lead compounds is easy. When mixed with carbonate of soda and heated on charcoal in the reducing flame they yield malleable globules of metal and a yellow oxide-ring. Solutions of lead salts (colourless in the absence of coloured acids) are characterized by their behaviour to hydrochloric acid, sulphuric acid, and chromate of potash. But the most delicate precipitant for lead is sulphuretted hydrogen, which produces a black precipi tate of sulphide of lead, insoluble in cold dilute nitric acid, less so in cold hydrochloric, easily decomposed by hot hydrochloric acid with formation of the characteristic chloride. Statistics. The lead, pig or sheet, imported into Great Britain during the year 1880 amounted to 95,202 tons, and during 1881 to 3,400 tons. In 1831 there were 12,824 tons exported to China, 355 to Russia, 4715 to Australia, 3390 to France, 3349 to British India, 1041 to Germany, and 8837 toother countries. The following table exhibits the production of lead during 1876 : Tons. Spain 101,522 Germany 82,772 Great Britain 59,606 United States 57,210 France 21,339 The importation and production of lead in the United States were in the years stated respectively as follows : Tons. Italy 9000 Greece 8000 Belgium 7375 Austria 4291 Russia ,. 1083 Imported. Produced. 1SGS Tons. 3 2^5 Tons. 14 630 1869 35 111 (max ) 15 650 1878 285 81 304 (W. D.) LEADVILLE, a flourishing mining town of the United States, capital of Lake county, Colorado, is situated at a height of 10,200 feet above the sea, on a narrow plateau between the Saguache or Continental Divide and the Park Range of the Rocky Mountains, about 70 miles south-west of Denver. It is connected with Denver by a branch of the Union Pacific Railway (172 miles), and by the Denver and Rio Grande Railway (279 miles). Though a place of 14,820 inhabitants at the census of 1881, Leadville was then the creation of scarcely more than three years. As early as 1860 gold placers were discovered in the neighbour hood, and for a little time the settlement of Bough Town, as it was then called, was a busy spot in this thinly peopled region. But the gold was soon exhausted ; and, though it was vaguely understood that the heavy black sand which had often proved troublesome to the gold-washers was more or less argentiferous, it was not till 1877 that the first practical attempt to turn it to account was made. No sooner, however, was the real character of the ore ascertained than eager adventurers rushed to Leadville by thousands. In August 1877 there were not more than twenty shanties on the site of the town ; but the population rapidly increased, and in less than two years numbered upwards of 12,000. The first smelting furnace was set to work in October 1877. It has been estimated that up to the close of 1880 the value of the metals extracted from the soil at Leadville exceeded 35,700,000 : 1860-73, gold from placers ... $6,400,000 1874, gold and silver 145,000 1875, do. do 113,000 1876, gold, silver, and lead ... 85,200 1877. gold, silver, and lead... $555,330 1873, do. do. ... 3,152,925 1879, do. do. ... 10,189,521 1880, do. do. ... 15,095,153 Its site consists for the most part of a porphyritic rock resting on a strongly silicified dolomite popularly called &quot;limestone&quot;; and the brown sand, the source of the wealth of Leadville, is sometimes found just below the surface of the soil, sometimes at a depth of several hundred feet. None of the streets maintain the same level throughout, the contour lines of the declivity on which they are built usually running at right angles. Of the dwelling-houses the vast majority are of wood ; but among the many substantial brick structures are an opera-house, a Catholic church, and several bank buildings. Water, brought from the higher grounds, is distributed by a regular system of mains ; the principal streets are macadam ized with slag ; there is a well-organized fire department and an efficient police force. The city has 6 churches, 7 schools, 3 daily and 2 weekly newspapers, and 6 banks, and is the centre of supply for a large outlying mining region, the value of its general and min ing business averaging for 1880 and 1881 over $40,000,000 yearly. LEAKE, WILLIAM MARTIN (1777-1860), antiquarian topographer, was born in London, January 14, 1777. After completing his education at the Royal Military Aca demy of Woolwich, and spending four years in the West Indies as lieutenant of marine artillery, he was sent by the Government to Constantinople to instruct the Turks in this branch of the service. A journey through Asia Minor in 1800 to join the English fleet at Cyprus inspired him with an interest in antiquarian topography, which he had afterwards frequent opportunities of gratifying. In 1801, after travelling across the desert to Egypt, he was, on the expulsion of the French, employed in surveying the valley of the Nile as far as the cataracts ; but having sailed with the ship engaged to convey the Elgin marbles from Athens to England, he lost all his maps and observations when the vessel foundered off the island of Cerigo. Shortly after his arrival in England he was appointed to survey the west coast of Albania and the Morea, with the view of assisting the Turks against attacks of the French from Italy, and of this he took advantage to form a valuable collection of coins and inscriptions, and to explore many ancient sites. In 1 807 he was made prisoner at Salonica; but, obtaining his release the same year, he was sent on a diplomatic mission to AH Pasha, whose confidence he completely won, and with whom he remained for more than a year as the representative of England. In 1815 he retired from the army, in which he held the rank of colonel, devoting the remainder of his life to topographical and antiquarian studies, the results of winch were given to the world in the following volumes: Topography of Athens, 1821; Journal of a Tour in Asia Minor, 1824 ; Travels in the Morea, 1830 ; Travels in Northern Greece, 1835 ; and Numismata