Gold-antimony compounds

He examined a gold-containing ore from Transylvania which had previously been thought to be an antimony compound. His work indicated that the substance was actually gold and a new substance. A sample was sent to Martin Heinrich Klaproth who confirmed the discovery of the new element and named it tellurium after the Latin word tellus which means earth. Te is rare, sometimes found free in nature, and in ores such as sylvanite (AgAuTc4) and calaverite (AuTez). It also occurs in low concentrations in sulfidic copper ores. 

Besides powdered metals, certain metallic compounds are sometimes used for the same purposes, e.g., stannic sulphide (mosaic gold), antimony sulphide (iron bronze) and various oxygenated compounds of tungsten (tungsten bronzes). 

The case intermediate between congruent and incongruent melting occurs when the point of intersection of the two curves coincides with the indifferent point of one of them. One example of this behaviour is provided by the system gold + antimony which forms an addition compound AugSb. 

CE is the equilibrium curve for the compound A,fiy— in the example under consideration x = and y = 1—with the submerged maximum at D. The point D is not realised in practice because the compound decomposes completely at E into sohd picric acid and liquid benzene. The point E is spoken of as the incongruent melting point of the compound (since the composition of the liquid is not the same as that of the original compound) or as the transition point. The ctuve EB represents the equilibrium between solid B and the liquid. This system is rarely encountered among compounds, but other examples are acetamide - salicylic acid and di-methylpyrone - acetic acid it is, however, comparatively common in alloy systems e.g., gold - antimony, AuSbj). 

In contrast, the introduction of inorganic complexes as therapies was usually based on an observed medicinal effect. Two of the earliest inorganic remedies involved the use of mercurous chloride as a diuretic, and iron complexes as mineral supplements, introduced about 500 years ago. More recently, gold complexes have been used as antibacterials, in particular for the treatment of tuberculosis at the beginning of the twentieth century. Other traditional inorganic drugs include the use of arsenic complexes, such as arsephenamaine, to treat syphihs [1] and antimony compounds for the treatment of leishmaniasis. 

Bromine has a lower electron affinity and electrode potential than chlorine but is still a very reactive element. It combines violently with alkali metals and reacts spontaneously with phosphorus, arsenic and antimony. When heated it reacts with many other elements, including gold, but it does not attack platinum, and silver forms a protective film of silver bromide. Because of the strong oxidising properties, bromine, like fluorine and chlorine, tends to form compounds with the electropositive element in a high oxidation state. 

The pyrometaHurgical processes, ie, furnace-kettle refining, are based on (/) the higher oxidation potentials of the impurities such as antimony, arsenic, and tin, ia comparison to that of lead and (2) the formation of iasoluble iatermetaUic compounds by reaction of metallic reagents such as 2iac with the impurities, gold, silver and copper, and calcium and magnesium with bismuth (Fig. 12). 

Metals less noble than copper, such as iron, nickel, and lead, dissolve from the anode. The lead precipitates as lead sulfate in the slimes. Other impurities such as arsenic, antimony, and bismuth remain partiy as insoluble compounds in the slimes and partiy as soluble complexes in the electrolyte. Precious metals, such as gold and silver, remain as metals in the anode slimes. The bulk of the slimes consist of particles of copper falling from the anode, and insoluble sulfides, selenides, or teUurides. These slimes are processed further for the recovery of the various constituents. Metals less noble than copper do not deposit but accumulate in solution. This requires periodic purification of the electrolyte to remove nickel sulfate, arsenic, and other impurities. 

Rubidium metal alloys with the other alkaU metals, the alkaline-earth metals, antimony, bismuth, gold, and mercury. Rubidium forms double haUde salts with antimony, bismuth, cadmium, cobalt, copper, iron, lead, manganese, mercury, nickel, thorium, and 2iac. These complexes are generally water iasoluble and not hygroscopic. The soluble mbidium compounds are acetate, bromide, carbonate, chloride, chromate, fluoride, formate, hydroxide, iodide. 

The research journals are the primary place where research results are first published. The prices of compounds change rapidly, and are to be found in journals instead of books. The New York Times finance page lists a number of commonly traded metals (aluminum, antimony, copper, gold, iron, lead, mercury, platinum, silver, zinc), food (corn, soya, wheat, rice, sugar), fuels (fuel oil, gasoline, natural gas), and textile (cotton, wool). The Chemical Market Report is a weekly journal that lists the prices of many chemical substances in a supplement, which depend strongly on purity and intended use. 

Silver is a white, ductile metal occurring naturally in its pure form and in ores (USEPA 1980). Silver has the highest electrical and thermal conductivity of all metals. Some silver compounds are extremely photosensitive and are stable in air and water, except for tarnishing readily when exposed to sulfur compounds (Heyl et al. 1973). Metallic silver is insoluble in water, but many silver salts, such as silver nitrate, are soluble in water to more than 1220 g/L (Table 7.3). In natural environments, silver occurs primarily in the form of the sulfide or is intimately associated with other metal sulfides, especially fhose of lead, copper, iron, and gold, which are all essentially insoluble (USEPA 1980 USPHS 1990). Silver readily forms compounds with antimony, arsenic, selenium, and tellurium (Smith and Carson 1977). Silver has two stable isotopes ( ° Ag and ° Ag) and 20 radioisotopes none of the radioisotopes of silver occurs naturally, and the radioisotope with the longest physical half-life (253 days) is "° Ag. Several compounds of silver are potential explosion hazards silver oxalate decomposes explosively when heated silver acetylide (Ag2C2) is sensitive to detonation on contact and silver azide (AgN3) detonates spontaneously under certain conditions (Smith and Carson 1977). 

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