Analysis of information sources in references of the Wikipedia article "Pot boiler" in English language version.
The hearth fire has handed down one relic of antiquity, the ' pot-boiler '. The pot-boiler was a roughly rounded stone, usually flint, which was made red hot and then flung into the water contained in the primitive cauldron or in a puddled hollow in the soil. By this means flesh was boiled, however inefficiently. Or, again, the meat was grilled or baked over the heated stones. The use of the pot-boiler for heating water was continued until late in the historic period.
