Element Cadmium, Cd, Transition Metal. 1124; the formula of the element in the vaporous state is therefore Cd. Forms only one elementary ion, divalent cadmion, Cd. The metal dissolves, although very slowly, in aqueous acids with formation of this ion. Cadmion is colourless, and acts as a rather virulent poison on the lower and higher organisms. Its heat of formation from the metal is 77 kj. Is soluble in excess of ammonia. The solution contains complex cadmium-ammonia ions, Cd. Of the salts the sulphate .

Element Nickel, Ni, Transition Metal. Unlike cobalt, which is not employed in the metallic state, metallic nickel is a material which is greatly used. It was formerly used only for alloys; thus German silver is an alloy of nickel with zinc and copper. Some decades ago, however, the difficulties caused by the high temperature of fusion of nickel. The electrical deposition of a metal depends on the fact that at the cathode of a circuit, the cations pass from the state of ions into the neutral state.

Element Palladium, Pd, Transition Metal. Was discovered by William Hyde Wollaston in 1803, also in raw platinum, in the part soluble in aqua regia. When Wollaston separated some quantity of the metal, he, without reporting about the discovery, distributed anonymous advertising about new metal named palladium. This element was named by Wollaston in 1804 after the asteroid Pallas, which was discovered by named by astronomer Heinrich Wilhelm Matthäus Olbers two years earlier.

On account of its remarkable properties and of its occurrence in the metallic state, silver. In the pure state silver is a white tenacious metal, which can be readily drawn into wire, and made into very thin sheets by rolling or hammering. For use it is alloyed with 10 per cent of copper in order to make it harder. It conducts heat and electricity very well, and occupies, in this respect, the first place among the metals. Is also found in native form.

Element Zinc, Zn, Transition Metal. From the metals of the iron group, to which it is in many respects similar, zinc. Differs in the fact that it cannot form any other stage of combination than that containing divalent ion. In this respect it forms an intermediate member between nickel, which has lost this property for the most part, and magnesium, in the case of which no trace of that property is present. Resist the influence of air and water fairly well.