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
Simultaneously extracted metals and Acid-volatile sulfide initially unbound to AVS (due to insufficient AVS in the sediment to "mop up" all the metal ions). The concentrations of metals in the acid solution can be measured by a number of analytical chemistry methods, including atomic emission spectrometry, atomic absorption spectrometry (AAS), or mass spectrometry. These are known as "simultaneously extracted metals" because they are the metals liberated from the sediment "while the volatilization of sulfide is occurring". Metals extracted from sediment by digestion, or with a different acid than HCl are "not" simultaneously extracted metals. By correcting appropriately for dilution, the SEM concentration in the sediment can