The large difference between the results would indicate some considerable source of error in part or all of the determinations. The first three determinations were made from a different specimen of cadmium from the last three. In the first three the cadmium used does not seem to have been purified and the cadmium chloride prepared from it was more or less tinted brown. In the last three a new specimen of metal was used which in Dumas’ words could reasonably be considered to be absolutely pure. The chloride prepared from it was colorless, well crystallized and perfectly soluble in water. In order to show clearly the wide discrepancy between the results obtained from the two specimens of cadmium which were used, the separate determinations are given in detail. At. Wt. CdCl₂ Ag. Cadmium. 1 2.369 2.791 112.322 2 4.540 5.348 112.347 3 6.177 7.260 112.759 4 2.404 2.841 111.756 5 3.5325 4.166 112.135 6 4.042 4.767 112.130 The average result of the first three determinations = 112.476. The average result of the last three determinations = 112.007. From Dumas’ own statement concerning the purity of the cadmium chloride analyzed, determinations 4-6 are much to be preferred to determinations 1-3 and the most probable value from Dumas’ work would be very nearly 112. Lenssen Journ. f. prakt. Chem. 79, 281. 1860, regarded the oxalate of cadmium as well adapted to the determination of the atomic weight of cadmium. A solution of cadmium chloride which had been purified by repeated crystallization was treated with an excess of a solution of pure oxalic acid. The cadmium oxalate formed was filtered off, washed, and carefully dried in the air at 150° C. until the last trace of water was removed. 1.5697 grams cadmium oxalate gave 1.0047 grams cadmium oxide. If the atomic weight of oxygen = 16, ” ” ” ” carbon = 12.003, ” ” ” cadmium = 112.043. The average of the three determinations using the above values for oxygen and carbon is 112.067. Maximum, 112.304. Minimum, 111.911. Mean, 112.067. The small amount of material used in each determination, the small number of determinations made, and the rather large difference between the highest and lowest result are objectionable. There are certain weak points in the method but to these reference will be made later. Huntington, Proc. Amer. Acad. 17, 28. 1882, working with Cooke, made two series of determinations of the atomic weight of cadmium. In the first series the relation between cadmium bromide and the silver bromide formed from it was determined. In the second, the relation between cadmium bromide and the silver required to precipitate the bromine. The cadmium bromide was prepared by dissolving the carbonate in hydrobromic acid and subliming the product in a stream of carbon dioxide.