This thesis was undertaken to demonstrate the practical utility of measuring the efficiency of a Heine Boiler, installed in the Power Plant at the Missouri School of Mines, by the amount of CO₂ in the flue gases. The tests were made on a new boiler which had recently been installed in the Power Plant. The boiler and setting being new, the tests should show a high percentage of CO₂ in the flue gases and a high evaporative efficiency by the boiler --page 3