Mercuric sulphide

Mercury Mercuric iodide Mercuric nitrate Mercuric oxide Mercurous nitrate Mercuric sulphate Mercuric sulphide Mercurous sulphate... 

The red form of mercuric sulphide once popular as an inorganic colouring agent for rubber. Vertical Continuous Vulcanisation... 

It is interesting to note that exactly the same interference occurred for both organic and inorganic mercury standards, since methyl mercuric chloride does not directly react with sodium sulphide to form mercuric sulphide. Therefore the interference could not be the result of incomplete digestion of mercuric sulphide or CH3Hg+. 

Experiment.—Phenyl isothiocyanate (0-5 c.c.) is heated for some time in a test tube with an equal volume of yellow mercuric oxide. Heating is continued until the isothiocyanate boils. The yellow oxide is converted into black mercuric sulphide and at the same time the extremely pungent odour of jphenyl cyanate is observed its vapour has a powerful lachrymatory effect. 

L. Bailey, J. Wilson, S. Kaipel and M. Riley, Application of chloride electrodes based on mercurous chloride/mercuric sulphide, ia Ion-Selective Electrodes (ed. E. Pungor and L Buz5s), Conference 1977, Akad6miai Kiad6, Budapest (1978), p. 201. 

He remarked that the gas is soluble in water that it corroded corks yellow as if they had been treated with nitric acid that it bleached paper coloured with litmus that it bleached green vegetables, and red, blue, and yellow flowers nearly white, and the colour was not restored by treatment with acids or alkalies that it converted mercuric sulphide into the chloride and sodium hydroxide, common salt etc. 

Mercury fulminate undergoes rapid decomposition by the action of ammonium sulphide to form mercuric sulphide. The fulminate dissolves in sodium thiosulphate, according to the reaction ... 

When sulphide of hydrogen gas is passed to saturation through a solution of protoxide of meroury, the white compound which appears at an early Btage of the operation is destroyed, and the black precipitate then consists solely of mercuric sulphide, which, when collected, dried, and heated in a retort, yields a fine crystalline sublimate of cinnabar. These two bodies, therefore, the black and the red, are allotropio modifications of one substance, Hg S. 

The stability of the sulphides other than those of the alkali metals, the alkaline earth metals and aluminium, ranges from that of manganese sulphide, which is easily decomposed by dilute acids and slowly by ordinary steam, to that of mercuric sulphide or molybdenum sulphide, which resist the action of concentrated hydrochloric acid solution. 

Mercury Thioarsenates.—When an alkali orthothioarsenate is added to an aqueous solution of a mercurous salt, a black precipitate of mercurous sulphide separates and a thioarsenate is formed in solution. Berzelius 3 thought this to be the pyro-salt which, when obtained by evaporation and heated, lost mercury and formed the mercuric pyro-salt. Heubach,4 however, stated that mercurous orthothioarsenate was formed and that this was decomposed by excess of mercurous salt to mercurous sulphide and arsenic acid. The mercuric salts are more stable. 

In practice sufficiently exact results are obtained by weighing the sulphides freed from excess of sulphur by successive washings with alcohol, ether and carbon disulphide, then dissolving the antimony sulphide in an alkaline polysulphide, and weighing the mercuric sulphide after again removing excess of sulphur. 

The principal red and yellow pigments are Lead chromate chrome yellow, orange and red), zinc chromate zinc or buttercup yellow), barium chromate lemon yellow or yellow ultramarine) various products based on jerric oxide, hydrated (yellow) or anhydrous (red), both natural yellow and red ochres) and artificial Mars yellow, English red, etc.) red oxide oj lead minium or red lead) mercuric sulphide cinnabar, vermilion) antimony oxysulphide antimony cinnabar) cadmium sulphide cadmium yellow) basic lead antimonate Naples yellow). 

Cinnabar is mercuric sulphide obtained by sublimation and vermilion the same sulphide obtained in the wet way the former is more or less deep red and the latter bright red (scarlet). 

Free Mercury and Mercuric Nitrate.—In absence of lead compounds, free mercury Or -mercuric nitrate may be detected by shaking the vermilion with nitric acid diluted to twice its volume, filtering the solution and treating with hydrogen sulphide in presence of mercury or mercuric nitrate, a black precipitate is obtained. If, however, lead compounds are present, the precipitate should be examined by the ordinary methods of qualitative analysis to ascertain if it contains mercuric sulphide. 

Mercuric sulphide is conveniently made by direct synthesis from the elements. Two modifications of this compound are known, one black, which is formed first in this preparation and also by precipitation of mercuric and sulphide ions the other a brilliant red (vermilion), which is more stable and into which the black form tends to change. 

When, at the end of about a week, the mass has changed to a pure red color, wash it by decantation (see Note 5 (6), page 10) in a 600-cc. beaker. Most of the excess of sulphur is floated off. Then rinse the red sulphide back into the evaporating dish, leaving behind in the beaker any lumps of black sulphide or globules of mercury. Boil the red sulphide with 50 cc. of saturated sodium sulphite solution to remove the last of the uncombined sulphur wash by decantation with boiling water and collect the mercuric sulphide on a suction filter. Dry the product on the hot plate and preserve it in a 2-ounce cork-stoppered bottle. 

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