After having done the work which has just been described, we are in a position to turn to the oxalate method, which is the first method described in this paper. It involves the decomposition of cadmium nitrate, and is therefore affected by an error from this source, only it is not as large as in case of the oxide method. If 2.95650 grammes of cadmium oxide prepared in a porcelain crucible contain .00081 grammes of impurity, an error of −.24 of a unit would be introduced in the atomic weight as determined by the oxide method or +.10 in case the oxalate method were employed. That is the oxalate should give about 112.48 for the atomic weight of cadmium, but it really gives a very much lower result. Morse and Jones obtained 112.04 ± .035 by it, while Partridge obtained 111.81 ± .035 by it. If we take 112.38 for the atomic weight of cadmium, there appears to be a second error of .44 of a unit in the method as used by Morse and Jones, while Partridge’s result indicates an error of .57 of a unit. Partridge only moistened the oxide obtained from the oxalate with a few drops of nitric acid before making the final heating, and it seems probable therefore that he made no appreciable error on account of the final oxide retaining products of decomposition from cadmium nitrate. The most probable cause of this large error seems probably to be incomplete dehydration of the oxalate, or reduction to metal during the decomposition of the oxalate, and subsequent volatilization of some of it, or a combination of both of these. The nine determinations given in the earlier part of this paper of course vary so much that they are of no value whatever in determining the atomic weight. The reason that the first four are low is probably due in part to sublimation of cadmium, for on dissolving the resulting oxide in nitric acid a considerable quantity of metal was noticed in each case. In the others, the temperature was kept lower, and the decomposition took a longer time. No metal was observed on taking up in nitric acid. To be certain of what the cause of error is would require some very carefully conducted experiments, but as there are a number of much more reliable methods for determining the atomic weight of cadmium, it does not seem desirable to spend the time required in making them. It should be mentioned that Lenssen, in 1860, first employed this method. He made three determinations. 1.5697 grms of cadmium oxalate giving 1.0047 grammes of oxide, which gives a value of 112.043 for the atomic weight of cadmium . The difference between the highest and lowest determination was .391 of a unit. Other Methods