It holds its own, however, when base bullion contains bismuth in appreciable amounts, as in the Pattinson process bismuth follows the lead to be cupelled, while in the Parkes process it remains with the desilverized lead which goes to market, and lead of commerce should contain little bismuth.
The original Pattinson process has been in many cases replaced by the LuceRozan process (1870), which does away with arduous labour and attains a more satisfactory crystallization.
A basic chloride, Pb(OH)Cl, was introduced in 1849 by Pattinson as a substitute for white lead.
In 1833 Pattinson invented his process by means of which practically all the silver is concentrated in 13% of the original lead to be cupelled, while the rest becomes market lead.
Of these the Pattinson process has become subordinate to the Parkes process, as it is more expensive and leaves more silver and impurities in the market lead.