Sulfids of arsenic

Figure 13.17 Molecular structure of some sulfides of arsenic, stressing the relationship to the AS4 tetrahedron (point group symmetry in parentheses).

Reactions of the various sulfides of arsenic call for little further comment. AS2S3 bums when heated in air to give AS2O3 and SO2. Chlorine converts it to ASCI3 and S2CI2. It is insoluble in water but dissolves readily in aqueous alkali or alkali-metal sulfide solutions to give thioarsenites ... 

Sulfides of arsenic and antimony are brightly colored, which has given rise to their use as pigments. Some of the sulfides, selenides, and tellurides of arsenic and antimony also function as semiconductors. 

A powder which burns with a green flame is obtained by the addition of nitrate of baryta to chlorate of potash, nitrate of potash, acetate of copper. A white flame is made by the addition of sulfide of antimony, sulfide of arsenic, camphor. Red by the mixture of lampblack, coal, bone ash, mineral oxide of iron, nitrate of strontia, pumice stone, mica, oxide of cobalt. Blue with ivory, bismuth, alum, zinc, copper sulfate purified of its sea water [sic]. Yellow by amber, carbonate of soda, sulfate of soda, cinnabar. It is necessary in order to make the colors come out well to animate the combustion by adding chlorate of potash.15... 

Sulfides of arsenic, alkalies sulfides with halide, oxide, hydroxide, H2O. 

Britzke, E. V., Kapustinsky, A. F., and Tschenzowa, L. G., 1933, The affinity of metals for sulfur. Part III. Combustion- and formation-enthalpies of the sulfides of arsenic and the compounds AS2O3 AS2O5 and As203,S03 Zeitschrift fur Anorganische Chemie, v. 213, p. 58-64. 

Weller, W. W., and Kelley, K. K., 1964, Low-temperature heat capacities and entropies at 298.15 °K of sulfides of arsenic, germanium, and nickel U.S. Bureau of Mines Report Investigations 6511, 7 p. 

Telation to sulfur that the oxids and hydroxids do to oxygen. "The two sulfids of arsenic, ASjSj and ASaS , correspond to the two oxids, ASjOs and ASaSs, and the hydrosulfld of potassium, -KHS, corresponds to the hydroxid, KHO. 

When the discovery became known, a factory owner, K. S. L. Hermann in Schone-beck, and a Medidnal Counsellor, Dr J. C. H. Roloff in Magdeburg, contacted Professor Stromeyer. Dr Roloff had made a pharmacy inspection some years earlier and confiscated zinc oxide, as it seemed to contain arsenic. From an add solution of the oxide, hydrogen sulfide in fact predpitated a yellow sulfide, identified as arsenic sulfide. The zinc oxide had been manufactured at Hermann s fadory from a Silesian calamine ore. The two gentlemen now sent to Professor Stromeyer both zinc oxide, prepared from the ore from Silesia, and the yellow sulfide with supposed content of arsenic. Stromeyer could rapidly state that the yellow substance was not the sulfide of arsenic but a sulfide of the metal he himself had discovered. 

The sulfides of arsenic and antimony have been known as minerals since antiquity, and they attracted great interest from the alchemists . The alchemistic symbolism expressed something typical for both elements, as is shown in Figure 46.1. Bismuth was also examined in an alchemistic way, but soon became a metal for practical, technical use. 

This category includes the sulfides of arsenic, antimony, tin, tungsten and molybdenum as demonstrated by the solubility of their sulfides in yellow ammonium polysulfide. Such compounds as (NH4)8AsS4, (NH4)aSbS4,... 

Sandaraca, generally interpreted as the orange-red sulfide of arsenic, realgar, is mentioned by all the classical sources though none elaborate on its provenance much beyond that it came fiom mines . Vitruvius (first century bc) says that these mines were in Pontus (which, in ancient times, was the name of the north-eastern province of Asia Minor, a long and narrow strip of land on the southern coast of the Black Sea, Pontus Euxinus). and it is certainly plausible that the volcanic regions south of this area were a source of this mineral. 

Arsenic is another metal known to the ancients with toxic as well as medicinal properties. The sulfides of arsenic, which were roasted, were described by Dioscorides in the first century A.D. as medicines as well as colors for artists. There is evidence that arsenic was used as a poison in Roman times (poisonous nature of arsenic compounds, which were used in various recipes. Paracelsus, the Swiss physician, used arsenic compounds as medicinal agents (9). Arsenic was widely used as a pesticide in the form of calcium arsenate following the turn of the 20 century. 

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