He then compares active oxygen with the antozone of Schönbein and says that several of the properties of antozone can be ascribed to active oxygen above all that property of antozone of oxidizing water to hydrogen dioxide. The only difference between the two being that active oxygen has but a momentary existence while antozone was supposed to be capable of isolation.
Baumann then describes results obtained by himself which enable us to clearly distinguish between active oxygen and ozone. Starting from the observation of Remsen[18] and Southworth that carbon monoxide, at ordinary temperatures, is not oxidized by ozone, he suspected that active oxygen would readily effect its oxidation. Palladium hydrogen was therefore sealed up in a capacious glass tube with a few cubic centimeters of clear lime water and a mixture of carbon monoxide and oxygen free from carbon dioxide. At first the lime water remained clear, but after several hours a cloudiness in the lime water became visible and after several days a precipitate of calcium carbonate settled to the bottom of the tube. He then repeated the experiment in a modified form. From a gasometer, containing a mixture of three volumes of oxygen and one of carbon monoxide free from carbon dioxide a slow current of gas was passed, first into a wash bottle containing a clear solution of baryta water, then into a tube containing palladium hydrogen. Then the gases were again passed through a wash bottle containing baryta water. After the current had been passing for four hours, the first baryta water was still perfectly clear, but the second showed a distinct cloudiness of barium carbonate, which slowly increased in the course of twelve hours. The baryta water in the first wash bottle remained clear even to the end of the experiment.
The different behavior of ozone and active oxygen was then shown by the following experiment:—“A slow current of air free from carbon dioxide was passed into a flask containing moist phosphorus, from there into a second flask where the ozonized air came in contact with a somewhat slower current, consisting of a mixture of three volumes of oxygen to one of carbon monoxide, carefully purified from carbon dioxide. From the second flask the gases were passed through a clear solution of baryta water.” “After all carbon dioxide had been removed from the apparatus the baryta water remained perfectly clear (völlig klar) after the gases had passed through for six hours.” “But, on the other hand, if the mixture of carbon monoxide and oxygen was passed into the first flask, containing the moist phosphorus and in which according to our theory active oxygen must occur, then the result is quite different, the baryta water becomes cloudy in a short time and in the course of an hour there is formed an abundant precipitate (‘reichlicher Niederschlag’) of barium carbonate.”
From these results he concludes that active oxygen may be detected by its power of oxidizing carbon monoxide, and states that this fact enables us to decide whether in oxidations effected by ozone there occur free atoms of oxygen.
Closely related to these experiments of Baumann are those of Professor Remsen[19] on the transformation of ozone into oxygen by heat. Now if atoms of oxygen can exist in the free state, it is difficult to see why transformation some of the oxygen atoms should not be in the free condition, and the statements of Baumann being true, if carbon monoxide is also present this should be oxidized. To test the question a gasometer was filled with carbon monoxide made from potassium ferrocyanide and sulphuric acid. Before entering the gasometer the gas was purified by passing through four wash bottles containing concentrated sodium hydroxide. Another gasometer was filled with pure oxygen. The ozone was produced by the silent electric discharge in a Wright’s tube connected with a Stoltz electrical machine. In detail the experiments were conducted as follows:—
A slow current of oxygen from the gasometer was passed through three woulfe bottles containing a concentrated solution of caustic soda and then into the ozonizer, the ozonized oxygen was then passed into a U tube, rubber joints between the ozonizer and U tube were found to be rapidly perforated and were replaced by a device of this kind:—
A, the tube from the ozonizer was introduced several inches into B, the tube leading to the U tube, and the joint C was closed by a cement composed of beeswax and paraffin. The carbon monoxide was passed through wash bottles containing caustic soda and finally through baryta water. The two gases were then brought together in a U tube placed in an air bath. After leaving the U tube the gases passed through perfectly clear lime water. Under these conditions the current of the gases was continued for an hour, and no precipitate was formed in the lime water.
“Separate experiments were made for the purpose of determining how readily the ozone was destroyed, and it was found that, even when the thermometer in the U tube indicated a temperature considerably below that stated as the decomposition temperature of ozone, and when highly ozonized oxygen was certainly entering the U tube, no ozone passed out, whether carbon monoxide was present or not in the tube at the same time.” The experiment as thus described was repeated several times, but always with the same result. “One modification of the experiment should also be mentioned in this connection. In order to get as good ozone as possible the ionizer was filled with oxygen and the current of gas stopper, the silent discharge was allowed to continue for a few minutes, then the gas was slowly passed into the heated U tube containing carbon monoxide. This interrupted current of oxygen was continued for about an hour but no oxidation of carbon monoxide to dioxide could be detected.” The conclusion that must necessarily be drawn from the result is that if carbon monoxide is a test for active oxygen, then when ozone is decomposed by heat there is no nascent or active oxygen formed.
The negative result obtained in the preceding investigation, naturally called in question the accuracy of Baumann’s statements in regard to the formation of active oxygen by the slow oxidation of phosphorus, and of palladium hydrogen in the presence of oxygen and water. The two experiments upon which he had based his conclusion have been described on pages 16 and 18. The first of these was that palladium hydrogen in the presence of oxygen and water effected the oxidation of carbon monoxide, the second, that when carbon monoxide was brought in contact with moist phosphorus and air oxidation was observed.