Original caption: Prevention of profits from going up the chimney stacks has always been a problem to smelters of lead and to those, like ourselves, who use lead to collect precious metals. At smelting temperature some of the lead carrying other metals with it is volatised and turned into fume, which if not caught would escape. Nowadays we are protected from such losses by the electrostatic precipitator but before the invention of this method we had a very substantial plant in operation. It was invented by the proprietors, John Wycliffe and Henry Joseph Wilson in collaboration with Andrew French, the chemist, in 1879. The invention was patented in Great Britain and the continent and there were at least five smelters in South Wales who took out licenses to use it and probably others. The long tube in the foreground was for cooling the furnace gases before they were dragged through the tanks or 'bubble boxes' behind by blowers in reverse or fans. In the bubble boxes there were thick planks in which many 1/4 inch holes were drilled by the works carpenters by hand brace and bit. These planks, fixed horizontally under water, caused the gases to break up and deposit the solids they contained. A slurry or mud resulted which had to be re-smelted.

Original at Sheffield City Archives: SSC2/13/21 (page 37).