Burning Mercury Thiocyanide Will Amaze You - Mercury(II) thiocyanate (Hg(SCN)2) is an inorganic chemical compound, the salt of Hg2+ and the thiocyanate anion. It is a stable solid at room temperature that has the appearance of white powder with chunks; it can also be grey in color, depending on purity. Mercury compounds are extremely toxic and protective equipment should be used whenever working with mercury thiocyanate. However, it is commercially available, though expensive. mercury thiocyanate is best known for its former use in pyrotechnics, as it will produce a large, winding snake when set on fire. This is known as the Pharaohs Serpent.  Though some people still use it for this purpose, it is generally avoided because of the production of toxic gases when this reaction occurs. -en.wikipedia.org-