Alloys arsenical

Lechtman, H. and S. Klein (1999), The production of copper-arsenic alloys (arsenic bronze) by co-smelting Modern experiment, ancient practice, /. Archaeol. Sci. 26, 497-526. 

Potassium, sodium, magnesium, and mercury can be distilled over niobium without formation of alloys arsenic, antimony, and tellurium do not form alloys below 500° to 600° C. 

Babbitt alloys -arsenic m [ARSENIC AND ARSENIC ALLOYS] (Vol 3)... 

The natural abundances of As, Sb, and Bi in the earth s crust are relatively low—about 0.0002% for As and about 0.000 02% for Sb and Bi. All three elements are found in sulfide ores and are used to make various metal alloys. Arsenic is also used to make pesticides and semiconductors, such as GaAs. Bismuth compounds are present in some pharmaceuticals, such as Pepto-Bismol. 

One of the most common applications for these two metalloids is for use when strengthening alloys, or mbrtures of elements, especially lead. Lead is a relatively soft, dense metal, so to make lead harder for applications such as bullets, either metalloid can be added to help make the resulting product stronger. This practice of alloying arsenic and antimony with lead dates back to the Bronze Age. 

Bullion commonly contains np to two per cent arsenic. Arsenic is preferentially oxidised in the softening or Harris processes, bnt more readily than antimony. Conseqnently when softener slag is reduced to form an antimonial lead alloy, arsenic can be retained in the residual slag from where it can be extracted by leaching and precipitation as arsenic trioxide or as calcium arsenite. Alternatively it can be extracted from canstic slags from the Harris process by leaching and precipitation with lime as calcium arsenite, which can contain around 20 per cent As. 

In the process of vacuum distillation dealing with copper base complex multi-component alloy, arsenic and antimony combines with copper forming a new compound, which brings about impossibility of separation. Distillation temperature and time have great influence on antimony, but have little influence on arsenic. 

Crude lead contains traces of a number of metals. The desilvering of lead is considered later under silver (Chapter 14). Other metallic impurities are removed by remelting under controlled conditions when arsenic and antimony form a scum of lead(II) arsenate and antimonate on the surface while copper forms an infusible alloy which also takes up any sulphur, and also appears on the surface. The removal of bismuth, a valuable by-product, from lead is accomplished by making the crude lead the anode in an electrolytic bath consisting of a solution of lead in fluorosilicic acid. Gelatin is added so that a smooth coherent deposit of lead is obtained on the pure lead cathode when the current is passed. The impurities here (i.e. all other metals) form a sludge in the electrolytic bath and are not deposited on the cathode. 

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