As early as 1700, miners in Brazil were aware of a metal they called ouro podre, ‘worthless gold,’ which is a native alloy of palladium and gold. However, it was not from this that palladium was first extracted, but from platinum, and this was achieved in 1803 by William Wollaston. He noted that when he dissolved ordinary platinum in aqua regia (nitric acid + hydrochloric acid) not all of it went into solution.
It left a residue from which he eventually extracted palladium. He did not announce his discovery but put the new metal on sale as a ‘new silver’. Richard Chenevix purchased some, investigated it, and declared it to be an alloy of mercury and platinum. In February 1805 Wollaston revealed himself as its discoverer and gave a full and convincing account of the metal and its properties.Palladium is a chemical element with the symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1803 by the English chemist William Hyde Wollaston.