Gold parting in 1860's Australia. It is able to refine gold up to 99.5% purity. The process involves blowing a stream of chlorine gas over and through a crucible filled with molten impure gold. Impurities in the gold form chlorides before the gold does and these insoluble salts are removed from the melt by skimming the surface. Invented by Emil Wohlwill in 1874, this produces the highest purity gold (99.999%). It is an electrolytic process using pure gold for the cathode (or titanium as a starter cathode) and chloroauric acid (gold chloride-hydrochloric acid) as the electrolyte; this is made by dissolving gold
Commodity chain metaphor for this concept because things are interconnected in so many ways, not just a mere straight line. This source explains global commodity chains in depth. Commodity chain A commodity chain is a process used by firms to gather resources, transform them into goods or commodities, and finally, distribute them to consumers. It is a series of links connecting the many places of production and distribution and resulting in a commodity that is then exchanged on the world market. In short, it is the connected path from which a good travels from producers to consumers. Commodity chains can be unique