The amalgamation proceeds very slowly, as the sole extraneous heat is that of the sun.
When the ore does not contain any considerable amount of free gold mercury is not, as a rule, used during the crushing, but the amalgamation is carried out in a separate plant.
Since many of the shorter ones are undoubtedly complete in themselves, it is natural to assume that the longer, which are sometimes very comprehensive, have arisen from the amalgamation of various originally distinct revelations.
The Reese River or pan-amalgamation process consists in drystamping crushed dried ore and dried salt (separately or together), charging them into a roasting furnace, and amalgamating the chloridized ore in an iron pan.
Vitruvius also gives a detailed account of the means of recovering gold, by amalgamation, from cloth into which it had been woven.