market potn.Metallurgy the last of a series of pots used in the Pattinson process, containing the purest fraction of lead (see also market-leadn.).
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1860 R. HuntUre's Dict. Arts (ed. 5) II. 664 The ‘market pot’, from which the desilverised lead is laded [sic] out.
1946 Thorpe's Dict. Appl. Chem. (ed. 4) VII. 223 The general method of working was to carry the purer metal towards one end..the last pot of which was called the market pot.