At the temperature at which concentrated sulphuric acid gives off dense white fumes cadmous hydroxide gives off all its water and passes over into a heavy yellow powder. At 150°C not a trace of water was liberated. Under the microscope the yellow powder was found to consist of minute translucent crystals. First determination of cadmium. Amount of substance used .08064 gr. ” ” cadmium found .07511 ” Cadmium. 93.14 per cent. Second determination of cadmium. Amount of substance used .10846 gr. ” ” cadmium found .10106 ” Cadmium. 93.17 per cent. The calculated percentage of metal in Cd₂O is 93.32 per cent. If water of too high temperature is employed in washing the subhydroxide, the presence of free metal in it can be detected under the microscope and by rubbing between agate surfaces. If the yellow suboxide is strongly heated it breaks up into a mixture of oxide and metal which possesses a distinctly green color. Towards acids the suboxide conducts itself like the subhydroxide. It is a fact of some interest in connection with the periodic arrangement of the elements, that the tendency toward the formation of a lower series of compounds which becomes so strongly developed in mercury begins to exhibit itself in some slight degree in cadmium. Notes on Crystals of Metallic Cadmium. The measurements of the cadmium crystals were made by Dr. Williams who has very kindly furnished me with his results. No reliable crystallographic description of the element cadmium seems thus far to have appeared--a fact due to the difficulty in obtaining suitable material. The crystals examined, although not capable of yielding entirely satisfactory results are nevertheless such as to make them of interest. In 1852 G. Rose noted the fact that distilled cadmium collected at the neck of the retort in drops which solidified as complex polyhedral aggregates[13] similar to those formed by zinc[14]. In 1874 Kammerer encountered the same aggregates which he explained as complicated isometric combinations[15]. This opinion was cited in 1881 by Rammelsberg[16]. In 1884 Brögger and Flink stated that in their opinion zinc, magnesium and probably cadmium were from analogy with beryllium which they had studied, hexagonal and holohedral.[17] [13] Pogg. Ann. 85, 293. [14] Amer. Chem. Journ. 11, 219. [15] Ber. d. deutch. Chem. Gesell. 1874, 1724. [16] Handb. d. krystallographisch physicalischen Chemie. I, 184. [17] Zeits & Kryst. 9, 236. This supposition has already been substantiated in the case of the two former elements[18] while the present material leads to the same result for the last named. The cadmium crystals were produced in the same manner as were those of zinc and magnesium measured before, viz; by distillation in a vacuum. The appearance of the tubes thus obtained was closely like that in the other cases. [18] Amer. Chem. Journ. 11, 225 and Ibid. 12, 225.