He proves by direct experiments that no active oxygen is formed during this process, and points out that the oxidations observed by Hoppe-Seyler and Baumann must have been brought about by the hydrogen dioxide. But this would not account for the oxidation of carbon monoxide, for it has been previously shown by Remsen[21] that hydrogen dioxide cannot oxidize carbon monoxide, not even when it is heated to its point of decomposition. Traube[22] therefore repeats Baumann’s experiment, he finds that palladium hydrogen in the presence of water and oxygen does oxidize carbon monoxide; but as he had shown that no active oxygen was formed during the process, and as the hydrogen dioxide could not cause the oxidation, he concluded that the palladium itself must play an important role in the reaction. By further experiments he soon became convinced that there are two stages in the process. 1st the palladium hydrogen acting on water and oxygen forms hydrogen dioxide, 2nd the hydrogen dioxide in the presence of palladium oxidizes the carbon monoxide. Traube[23] introduced into a glass flask containing carbon monoxide a dilute solution of hydrogen dioxide and a small piece of palladium foil, previously ignited, the action was allowed to continue for 22 hours after which the CO was replaced by air free from carbon dioxide. After leaving the flask the gas passed through a solution of barium hydroxide; an abundant precipitate was formed, showing that in this case the quantity of carbon dioxide formed was greater than in the first experiment, in which he used palladium hydrogen, water, oxygen and carbon monoxide. Traube’s conclusion is as follows:-- “The carbon dioxide obtained in Baumann’s experiments is not formed during the oxidation of the hydrogen of the palladium hydrogen, (there being formed by this action merely hydrogen dioxide and palladium free from hydrogen) but by the combined action of these last two substances on carbon monoxide.” “Therefore, the proof is given that the act of slow combustion (Autoxidation) has not in itself the power of making oxygen active.” The conclusion reached by Traube was tested by Professor Remsen and myself in the following way: A current of carbon monoxide was passed through several wash bottles containing solutions of caustic soda, then through a wash bottle containing clear baryta water, then into a flask containing a solution of hydrogen dioxide, containing a slight excess of hydrochloric acid. The flask also contained a small piece of palladium foil free from hydrogen. After leaving the flask the gas passed through a solution of baryta water, which was protected from the air by a U tube containing solid KOH. It was only necessary to pass the carbon monoxide through for a very short time to obtain an abundant precipitate of barium carbonate. We also noticed that under these conditions the palladium foil was dissolved.