Mercury silvering Mercury silvering Mercury silvering or fire gilding is a silvering technique for applying a thin layer of precious metal such as silver or gold (mercury gilding) to a base metal object. The process was invented during the Middle Ages and is documented in Vannoccio Biringuccio's 1540 book "De la pirotechnia". An amalgam of mercury and the precious metal is prepared and applied to the object which is then heated, sometimes in oil, vaporizing most of the mercury. The technique is dangerous since mercury is highly toxic, especially in its vapor phase. Mercury silvering can be detected through a variety of
Mercury(II) thiocyanate from dark graphite grey to light tan in color with the inside generally much darker than the outside. The reaction has several stages as follows: Igniting mercury thiocyanate causes it to form an insoluble brown mass that is primarily carbon nitride, CN. Mercury sulphide and carbon disulphide are also produced. 2Hg(SCN) → 2HgS + CS + CN Carbon disulphide combusts to carbon dioxide and sulphur dioxide: CS + 3O → CO + 2SO The heated CN partially breaks down to form nitrogen gas and cyanogen: 2CN → 3(CN) + N Mercury sulphide reacts with oxygen to form mercury vapour and