Stimulation of the Hill reaction by carbon dioxide

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Abstract
Experiments by Boyle purporting to show a CO2 stimulation of the Hill reaction were repeated. While Boyle''s results were confirmed they were considered not to be evidence of a CO2 effect per se. When alkali was not present in vessel center wells, the same rate of Hill reaction occurred with or without CO2. When alkali was present, some quinone distilled from the main compartment onto the alkali-soaked filter paper in the center wells. The resulting mixture consumed O3 at a rate comparable with the rate of O2 production in the Hill reaction. A report by Warburg and Krippahl of a CO2 stimulation of the Hill reaction similar to that of Boyle but using different materials and methods was confirmed. With manometry and experimental conditions as specified by Warburg and Krippahl 1.5-5% CO2 was found to enhance the rate of the Hill reaction by approximately 50%. Using mass spectrometry it was established that the CO2 effect was specifically on the rate of O2 evolution, not on O2 uptake; nor was a gas other than O2 evolved. Using tracer CO2 it was not possible to demonstrate a cyclic evolution and uptake of CO2 which had been postulated by other investigators.