departer

A departer was a skilled metallurgist who performed the final refining step in precious metal production, using chemical separation to divide gold from silver when the two were alloyed together. The work involved dissolving mixed metals in aqua fortis (nitric acid) to selectively attack and remove silver, leaving behind purified gold. This was essential chemistry in mint operations and the jewellery trade, particularly before the rise of electrolytic refining.

The process departers used relied on silver's solubility in dilute nitric acid while gold resists it. The metallurgist would heat the alloy in vessels, introduce the acid in carefully controlled stages, then filter and recover the gold residue. The spent acid, now containing dissolved silver nitrate, could be further processed to recover that metal. The work demanded precision with timing and temperature, and intimate knowledge of how different acid strengths behaved with varying alloy compositions.

As industrial refining evolved through the nineteenth and twentieth centuries, electrolytic cells and more automated separation methods displaced the departer's craft. By the 1920s, the role had largely vanished from active practice, though the chemistry remained unchanged. Precious metal houses still performed these separations, but now as standardized industrial processes rather than the skilled manual trade the departer once represented.

The term survives mainly in historical metallurgical texts and in the records of old mints and assay offices. Understanding what a departer did illuminates the chemical foundations of metal refining and the hierarchy of craft skills that once defined metalworking trades. The chemistry of aqua fortis refining itself remains valid; the departer's knowledge simply moved into the training manuals of modern refinery operators.