From these experiments it is clear that the oxidation phenomena which Hoppe-Seyler and Baumann attributed to active oxygen are really due to the combined action of palladium and hydrogen dioxide, and to suppose that atomic oxygen exists in the free state at any time during the process is entirely gratuitous. It remained to test the second of Baumann’s statements; namely that carbon monoxide in the presence of moist phosphorus and air is oxidized to carbon dioxide by the active oxygen formed by the slow combustion of the phosphorus. Leeds[24] also has on record an experiment on this subject, in which he claims that under these conditions oxidation takes place. In taking up the subject, therefore, Prof. Remsen[25] and myself have taken the greatest care to avoid all sources of error. We tried the effects of passing air alone freed from carbon dioxide over moist phosphorus and then into clear baryta water, Baumann[26] states that this can be done, and the baryta water remains perfectly clear, even if the current of air is passed for six hours. We obtained a precipitate immediately. Thinking this might be caused by the white vapors which are formed during the process, we passed the gas after its exit from the vessel containing the phosphorus through a layer of previously ignited asbestos. The layer of asbestos was between two and three feet in length and the air after having traversed it no longer contained any white fumes. From the asbestos tube the air passed into a solution of clear baryta water. A precipitate was formed at once and increased in quantity the longer the current continued. “It was tested for phosphoric acid and phosphorus in general but not a trace could be detected. The current of air over the phosphorus was continued for several days in order to obtain enough of the precipitate for examination and analysis. It proved to be nothing but barium carbonate.”