Derivatives of Gold and Nitrogen

The so-called " fulminating gold" has long been known, and derives its name from its explosive character. Its composition varies with the mode of preparation. Explosive products classed as fulminating gold are obtained by the interaction of ammonia or ammonium salts and auric oxide; by that of ammonia or ammonium carbonate and auric-chloride solution; and by that of ammonia and the sulphuric-acid and nitric-acid derivatives of gold. The colour of the product varies between green and brownish yellow; and on heating, percussion, or rubbing it decomposes explosively into gold, nitrogen, and ammonia. The explosive power is augmented by boiling with water or potassium-hydroxide solution, and by careful heating at 100° C. It is reduced by mixing the powder with salts of the alkali-metals or alkaline-earth metals, and with metallic oxides. Raschig assigns to the product obtained from auric oxide the constitutional formula NH=Au-NH₂, the union of both nitrogen atoms with gold being indicated by the small proportion of nitrogen eliminated by boiling with water, alkalies, or acids. He has shown the product obtained from auric chloride to consist of this substance with an admixture of a chloro-derivative, NH=Au-Cl.

Another method of preparation has been described by Jacobsen.

Silver nitrate reacts with aurichloric acid in accordance with the equation

4AgNO₃+HAuCl₄+3H₂O = Au(OH)₃,4AgCl + 4HNO₃.

The brown precipitate formed is converted by ammonia into fulminating gold, which after drying explodes violently downwards when touched with a knife. Jacobsen regards it as having the constitution Au(OH)₂NH₂ or (AuN,2H₂O),H₂O. When boiled with potassium- hydroxide solution, it is converted into a blackish-brown substance of even more explosive character, probably having the constitution Au(OH)₂NHAU(OH)₂.