Turns valve to start continuous flush of water into tub to wash foreign materials from stock.
Turns handwheel to actuate roller that kneads and turns stock in tub. Turns off water and roller after time necessary to reduce foreign material to required level. Drains water from tub and pumps specified amount of acid into tub to kill organisms in stock. Tests concentration of acid-sample in tub, using titration, burette, and pH indicator, and adds acid to tub when necessary. Drains acid from tub after prescribed time and washes stock with water.