An equal quantity of sulphuric acid was added to the crucible used as a tare and evaporated. After the metal had been dissolved, the platinum cone was lifted to one side and the excess of acid evaporated off. It was then heated in a glass air-bath for a long time at a temperature which was probably about 400°C. After the weight had become constant, the amount of free sulphuric acid was estimated by titration with a standard alkali using tropaeolin as an indicator. 1.25 milligrammes were found and this weight was subtracted from that found at the balance. Weighing were reduced to the vacuum standard, assuming the Sp. Grs. of cadmium and anhydrous cadmium sulphate[1] to be 8.54 and 3.0 respectively. The results were as follows: Footnote 1: Could not find any record of its Sp. Gr., 3.0 is assumed. Cd CdSO_{4} At. Wt. I. (112.35 can only be regarded as a preliminary experiment) II. 1.15781 2.14776 112.35 Discussion of the Results. These results agree fairly well with those obtained by the chloride and bromide methods. The second experiment is more trustworthy than the first. In it, we started with pure metal and the manipulations were so simple that no serious error could have been made in them. Hence it will only be necessary to consider the end-product, i.e., the cadmium sulphate. The titration showed that the sulphate was not basic owing to loss of sulphur trioxide, and after deducting the weight of the excess of sulphuric acid we must have left a weight of cadmium sulphate which is equivalent to the metal employed. The question now is, did it contain anything else and what would be its effect? Clearly the effect of water or any other impurity would be to lower the atomic weight found, hence the atomic weight must be at least as high as the experiment indicates. As the cadmium sulphate is deposited, at least the later part of it is from a strong sulphuric acid solution, it probably does not contain any water and in this case would fix a maximum value as well as the minimum value, and thus determine the atomic weight. It might be objected to the second experiment that the sulphuric acid found may have been present as SO_{3} and not as H_{2}SO_{4} as was assumed. This seems highly improbable, and even if it were so the error introduced would be only about .03 of a unit in the atomic weight. As the first determination was found practically neutral, it does not apply to it at all. The most probable conclusion from these experiments is that the atomic weight of cadmium is about 112.35. A more thorough study of this method would have been made if time had permitted it. The Oxide Method.