Mercury sulfide compounds

Mercury is a unique element. An extremely heavy metal, it is the only metallic element that exists in liquid form at room temperature. This silvery white metal is a good conductor of electricity, but it is a poor conductor of heat, which is unusual for metals. Scientists have shown that mercury has been known to humanity for thousands of years. People in ancient China knew of the metal, and samples of it have been found in Egyptian tombs dating back to 1500 b.c. While its name comes from the planet Mercury, its chemical symbol, Hg, comes from the Latin word hydragyrum, which means liquid silver. Mercury s primary ore is cinnabar, which is also known as vermillion. This ore, found chiefly in Spain and Italy, contains an abundance of mercury sulfide compounds. Mercury is extracted from cinnabar by heating the ore and then condensing the resulting vapor. 

The mercury sulfide compounds are undoubtedly the most important of the mercury group pigments as they include the red mineral cinnabar (HgS) and its synthetic analogue mercury(ll) sulfide, commonly known as vermilion q.v.). Two other crystal modifications of mercury(ll) sulfide occur, the hypercinnabar tyqie (P-HgS) and the metacinnabar type (a -HgS), the latter primarily significant as a black alteration product. Additionally, cadmium mercury sulfide ((Cd,Hg)S) is relevant in the context of cadmium sulfide pigments. 

The toxic nature of mercury and its compounds has caused concern over environmental pollution, and governmental agencies have imposed severe restrictions on release of mercury compounds to waterways and the air (see Mercury). Methods of precipitation and agglomeration of mercurial wastes from process water have been developed. These methods generally depend on the formation of relatively insoluble compounds such as mercury sulfides, oxides, and thiocarbamates. MetaUic mercury is invariably formed as a by-product. The use of coprecipitants, which adsorb mercury on their surfaces facihtating removal, is frequent. 

Merkuro-. mercurous, mercury (I), -azetat, n. mercurous acetate. mercury(I) acetate, -chlorld, n. mercurous chloride, mercury(I) choride. -chrom, n. (Pharm.) mercuro chrome, -jodid, n. n ercurous iodide, mer-cury(I) iodide. -nitrat, n. mercurous nitrate, mercury(I) nitrste. -oxyd, n. mercurous oxide, mercury(I) oxide, -salz, n. mercurous salt, mercury (I) salt, -sulfat, n. mercurouasulfate, mercury(I) sulfate, -sulfid, n. mercurous sulfide, mercury(I) sulfide, -verbindung, /. mercurous compound, mercury (I) compound. 

With this, the complex iron pigment does indeed deserve to be called insoluble, as only one part of dissolved Iron Blue can statistically be found in 100,000,000,000,000,000,000,000,000,000 parts of water (1029). The actual solubility would therefore be less by a factor of 102° as determined by Tananaev el al., which would come pretty close to values calculated for other so-called insoluble compounds, like mercury sulfide (HgS). However, one must consider that the chemistry of Fe3+ in aqueous solutions doesn t justify the terms dissolved or precipitated , since a multitude of complexes do exist in the... 

Before ad 1500, many alchemists thought that matter was composed of two "elements" mercury and sulfur. To impress their patrons, they performed an experiment with mercury sulfide, also called cinnabar, HgS. They heated the red cinnabar, which drove off the sulfur and left the shiny liquid mercury. On further heating, the mercury reacted to form a red compound again. Alchemists wrongly thought that the mercury had been converted back to cinnabar. What Hg(ll) compound do you think was really formed when the mercury was heated in the air What is the mass percent of mercury in this new compound What is the mass percent of mercury in cinnabar ... 

Mercury-cadmium pigments were developed in the early 1950s as a more cost-effective alternative to cadmium sulfoselenides. Mercury replaces part of the cadmium in the cadmium sulfide compound and eliminates the need for selenium. The resulting pigments range from deep orange to a maroon and offer a cleaner, brighter chroma than their cadmium counterparts. Manufacture is the same as for cadmium sulfides, except that mercury salts are added to the cadmium solution that is reacted with the alkali sulfide solution to cause precipitation. 

Exposure to neurotoxicants or neurotoxic chemical substances causes severe adverse health effects to the nervous system, which is very sensitive to organometallic compounds and sulfide compounds. These compounds disrupt the normal functioning of the central nervous system, peripheral nerves or sensory organs, and the conduction of nerve impulses. Thus, chemical substances are considered neurotoxicants when they induce a consistent pattern of neural dysfunction. The chemical substances include but are not limited to carbon disulfide, manganese, methyl mercury, organic phosphorous insecticides, tetraethyl lead, thallium, and trialkyl tin compounds. 

The natural global bio-geochemical cycling of mercury is characterized by degassing of the element from soils and surface waters, followed by atmospheric transport, deposition of mercury back to land and surface waters, and sorption of the compound to soil or sediment particulates. Mercury deposited on land and open water is in part revolatilized back into the atmosphere. This emission, deposition, and revolatilization creates difficulties in tracing the movement of mercury to its sources (WHO 1990). Particulate-bound mercury can be converted to insoluble mercury sulfide and precipitated or bioconverted into more volatile or soluble forms that re-enter the atmosphere or are bioaccumulated in aquatic and terrestrial food chains (EPA 1984b). 

Hydrogen chloride (98) Hydrogen cyanide (133) Hydrogen sulfide (135) Mercury and compounds (52) Methanol (137)... 

This pigment was described by Salter (1869) as a brighter, purer and clearer version of so-called orange vermilion, while Muckley (1880) stated that it was the same as orange vermilion but manipulated more carefully . Orange vermilion in turn was considered either merely mercury sulfide (i.e. identical to vermilion), a levigated form of vermilion or else compounded with chrome yellow (. v. normally lead chromate). 

Tablelr.1-177 Phonon frequencies/wavenumbers at symmetry points for mercury compounds. Mercury sulfide (HgS), 80 K, from infrared reflectance mercury selenide (HgSe), RT, from resonance Raman scattering mercury telluride (HgTe), 290 K, from neutron scattering...

The toxic effects of mercury and mercury compounds as well as their medicinal properties have been known for many centuries. In the first century AD, Pliny indicated the use of mercuric sulfide (cinnabar or vermilion) in medicine and in cosmetics. This compound was probably known to the Greeks in the time of Aristotle (13). 

Galen, a physician whose views outUved him by about a thousand years, died about 200 AD. He beUeved that mercurials were toxic, and did not use any mercury compound therapeutically. However, as a result of Arabian influence, the therapeutic uses of mercury were slowly recognized by Western Europe. In the thirteenth century mercury ointments were prescribed for treating chronic diseases of the skin. Mercury and its compounds, such as mercurous chloride, mercuric oxide, mercuric chloride, and mercuric sulfide, were used widely from the fifteenth to the nineteenth centuries, and to some extent in the twentieth century. During the first half of the twentieth century, the primary therapeutic uses of mercury included bactericidal preparations, such as mercuric chloride, mercuric oxycyanide, and mercuric oxide and diuretics, such as aryl HgX (Novasural) and mercurated ahyl derivatives (14). 

Mercury spills should be cleaned up immediately by use of a special vacuum cleaner. The area should then be washed with a dilute calcium sulfide solution. Small quantities of mercury can be picked up by mixing with copper metal granules or powder, or with zinc granules or powder. To avoid or minimize spills, some plants use steel trays as pallets so that a spih, whether of mercury or a mercury compound, is contained on the steel tray. 

When the mercury present in the atmosphere is primarily in the form of an organic mercury compound, it may be preferable to utilise an aqueous scmbber. This method is particularly useful for control of emissions from reactors and from dryers. For efficient and economical operation, an aqueous solution of caustic soda, sodium hypochlorite, or sodium sulfide is reckculated through the scmbber until the solution is saturated with the mercury compound. 

Deposits. Selenium forms natural compounds with 16 other elements. It is a main constituent of 39 mineral species and a minor component of 37 others, chiefly sulfides. The minerals are finely disseminated and do not form a selenium ore. Because there are no deposits that can be worked for selenium recovery alone, there are no mine reserves. Nevertheless, the 1995 world reserves, chiefly in nonferrous metals sulfide deposits, are ca 70,000 metric tons and total resources are ca 130,000 t (24). The principal resources of the world are in the base metal sulfide deposits that are mined primarily for copper, zinc, nickel, and silver, and to a lesser extent, lead and mercury, where selenium recovery is secondary. 

Sulfides, thiols, and proteinacious organic matter, particularly plasma and whole blood, seriously depress and may even aboHsh the germicidal action of mercury compounds (qv). As of this writing approved uses for mercurials are limited to contact lens cleaning fluids, spoilage prevention of stored... 

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