The oxides resulting from these determinations were always tested for oxides of nitrogen, sometimes by using meta phenylene diamine and at other times by sulphanilic acid and naphthylamine sulphate, but no traces were ever found. The average of the determinations made in porcelain crucibles is 112.08. Morse and Jones obtained the same figure or, if their results are reduced to the vacuum standard, 112.06, by the same method under the same conditions. The results of the determinations made in platinum crucibles are equally constant, but their average is 111.88 being .20 of a unit lower. Therefore, more oxide is obtained when platinum crucibles are used instead of porcelain ones. In two cases the platinum crucibles were weighed at the end of the determinations after the cadmium oxide had been removed. Their weight remained unchanged. The most probable explanation of these facts seems to be that something is retained in the oxide in both cases, but that the amount is greater in the determination made in platinum crucibles than in those in which porcelain ones were employed. We should expect this, because in porcelain crucibles some of the oxide is absorbed forming a silicate, and any volatile impurity must be expelled from this part of the oxide. Not finding oxides of nitrogen, it was thought that gases probably nitrogen and oxygen might be occluded although Richards and Rogers (Amer. Chem. Jour. 15, 567.) had examined cadmium oxide prepared from the nitrate and found only a trace of gas. Accordingly two specimens of cadmium oxide obtained in the above determinations were powdered in an agate mortar and boiled with water for some time in order to remove any adhering air. They were then dissolved in dilute hydrochloric acid from which the air had been removed by boiling. A small amount of gas was found in each case but not nearly enough to account for the difference of .31 unit in the atomic weight of cadmium between 112.38 and the oxide method. In fact not more than about one sixth of the amount required was found. It may be that the powdering of the oxide and then boiling up in water may have been to severe a treatment, and that the greater part of the occluded gas escaped during these processes. It seems that there is at least some error due to occluded gases in methods involving the decomposition of cadmium nitrate to oxide, but no satisfactory idea of its magnitude could be obtained from these two experiments as carried out.