Gold parting of the salt cementation process. This mixture is then added to an earthenware pot and layered with thin sheets of gold fold. The pot is then sealed and heated in a furnace. It was during the medieval period that distillation was discovered and the first description of nitric acid production was given by Pseudo-Geber in the "Summa perfectionis", 1330. Nitric acid is able to dissolve silver. The addition of sal ammoniac to nitric acid creates Aqua regia and this acid is able to dissolve gold. Both acids are used in the acid method of parting but the acids were expensive
Amphoterism different cations, such as zinc(II), which dissolves in base, from manganese(II), which does not dissolve in base. Lead oxide (PbO): Aluminium oxide (AlO) Stannous oxide (SnO) Some other elements which form amphoteric oxides are gallium, indium, scandium, titanium, zirconium, vanadium, chromium, iron, cobalt, copper, silver, gold, germanium, antimony, bismuth, and tellurium. Aluminium hydroxide is also amphoteric: Beryllium hydroxide Amphoterism In chemistry, an amphoteric compound is a molecule or ion that can react both as an acid and as a base. Many metals (such as copper, zinc, tin, lead, aluminium, and beryllium) form amphoteric oxides or hydroxides. Amphoterism depends on the