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
Wolffenstein–Böters reaction Wolffenstein–Böters reaction The Wolffenstein–Böters reaction is an organic reaction converting benzene to picric acid by a mixture of aqueous nitric acid and mercury(II) nitrate. The reaction, which involves simultaneous nitration and oxidation, was first reported by the German chemists Richard Wolffenstein and Oskar Böters in 1906. According to one series of studies the mercury nitrate first takes benzene to the corresponding nitroso compound and through the diazonium salt to the phenol. The presence of nitrite is essential for the reaction; picric acid formation is prevented when urea, a trap for nitrous acid, is added to the mixture. From then on