GOLD 860 GOLD GOLD, a triatomic metallic element, symbol Au; atomic weight, 196; specific gravity, 19.26; melting point about 1240° C, forming a green fluid which vol- atilizes at a higher temperature. Gold is a metal of a bright yellow color. It is very ductile; a grain of it can be drawn into a wire 50 feet long, and will gild two miles of fine silver wire. It is also very malleable; one grain can be beaten out to cover an area of 56.75 square inches. Gold does not oxidize or tarnish in the air, and is not acted upon by ox- ygen or water at any temperature; it is not dissolved by suli)huric, nitric, or hy- drochloric acid, but is dissolved by aqua regia, a mixture of nitric and hydro- chloric acids. Gold crystallizes in cubes, octahedra, and other forms belonging to a regular system. Gold forms two series of salts, aureus and auric; it has been detected in sea water. Gold can be puri- fied by melting it along with borax in a clay crucible, glazed inside with borax, and passing chlorine gas through the melted metal by means of a tobacco pipe stem; the other metals ■ are converted into chlorides, which rise to the surface. When the operation is finished, the gold is allowed to cool, and the fused chlo- M"^ DAV/OSOn 7eZ7feet very poisonous, acting like corrosive sublimate. Gold leaf is used by dentists for filling teeth. Mineralogy. — A metal crystallizing isometrically in octahedrons or dodecahe- drons, as well as acicular, filiform, re- ticulated, arborescent, and spongiform shapes. There are four varieties, (1) Ordinary, and (2) Argentiferous gold or electrum, (3) Palladium gold or por- pesite, (4) Rhodium gold. The gold prod- uct of the United States far exceeds that of any other land. Almost every State and Territory has yielded its share of the precious metal. By far the largest portions have come from California. Gold in Alaska was first reported by Tebenkof in 1848, but the first real important "find" was that of Joseph Juneau in 1880, near the site of the present town of Juneau. In August, 1896, J. F. Butler, a California miner, took out $10,000 in 10 days at a point 4 miles above Dawson. About the same time George W. Cormack dis- covered a rich field on the Klondike, in the Northwest Territory, reports of which caused a great rush to that re- gion in 1897-1898. Within two months after the discovery, $5,000,000 were taken out. Though the Klondike region OBSERVATORT CROSS SECTION OF COMSTOCK LODE AT SUTRO, NEVADA rides poured off. Pure gold is prepared by dissolving the metal in a mixture of nitric and hydrochloric acids; the solu- tion is evaporated to get rid of the ni- tric acid, then diluted with water and filtered; the gold is then precipitated by ferrous sulphate. 2AuCl3-i-6FeSOi= Au2 + Fe^CL + 2Fe2(S04)3. Pure gold is a very soft metal, therefore it is alloyed with silver, which gives it a greenish- yellow tint, or with copper, which gives it a yellowish-red color. Pharmacy. — Gold has been used in medicine for scrofulous diseases and for chronic alcoholism. Gold terchloride is attracted the most attention, it is a very small portion of the gold«-bearing region of Alaska and Canada. Colorado is also a rich gold-producing State. The largest gold production in the world is from the Transvaal, and other provinces of South Africa. Geology. — Gold has been found in slate, quartzite, sandstone, limestone, granite, and serpentine. In many cases it occurs in veins of quartz, but much more accessibly in drifts, which the breaking up of those quartz veins has helped to produce. In the Ural Moun- tains the drift is Newer Pliocene; in
