Goitre

(goi'tr.) (Med.) See BRONCHOCELE. Golconda, (göl-kōn'dah,) a celebrated city of India, in the Nizam's Dominions, under Brit. protection; N. Lat. 17° 22', E. Lon. 78° 25′. This place, once the C. of a wealthy and powerful kingdom, has now fallen in to decay,and is of importance only on account of its fortified position. G. has been long renowned for the diamonds cut, set, and polished by its lapidaries. Gold, (gold.) [A.S.] (Min.) A metallic element of a beautiful yellow color, soft, and extremely malleable and ductile. Sp. gr. 19-258 to 19-367. It melts at 2192° F., and volatilizes slightly at a little higher temperature. It does not tarnish in the air even when melted, and is unaffected by any single acid, but is di olved by chlorine water and mixtures which evolve chlorine, such as nitro-hydrochloric acid. It forms compounds with most of the other elements, but they are of comparatively slight importance. At. weight 196. Symbol, Au(from its Latin name Aurum). G. amalgamates the most readily of all the metals with quicksilver. When in a state of fusion, it very easily and very intimately combines with silver, and when mixed with that metal, will also run into a ma with iron. No metal destroys the malleability of G. so completely as lead: one two thousandth part renders it too brittle for rolling, and its very fumes produce a serious effect upon it. G. is widely distributed over the globe, and occurs in rocks of various ages from the Azoic to the Tertiary. Itis found with comparatively small exceptions in the veins of quartz that intersect metamorphic rocks. It is always very irregularly distributed, never in continuous pure bands of metal like many metallic ores. It occurs in the quartz in strings, scales, plates, and in ma es which are sometimes an agglomeration of crystals. It is mostly gathered, not directly from the quartz, but from the gravel or sands of rivers or valleys, or the slopes of hills or mountains whose rocks contain auriferous veins. Such deposits, called placer diggings in California, have been derived from the disintegration or wearing down of the rocks containing gold. G. is too soft to be used in a state of perfect purity. It is almost universally alloyed with copper, or with silver, in order to increase its hardne . In expre ing the finene of an alloy of gold, the ma is supposed to be divided into 24 parts; and the number of these consisting of pure gold is expre ed (see CARAT). Jewelry is generally made of 18 carat gold. Previous to the discovery of G. in California (1847) and Australia (1851), the world was to a great extent supplied with it from Mexico, Brazil, New Granada, Chili, Peru, Asiatic Ru ia, the Indian Archipelago, East and West coast of Africa, Hungary, and Transylvania. All these countries still produce G., but their total yield is only about one-third that of the U. States and Australia. In 1870 a new and very promising gold region has been discovered in the French island of New Caledonia. [s. 414]