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 Germanium, Ge, Metalloid. Matched those of the eka-silicon whose existence had been predicted in 1871 by Dmitri Mendeleev. By mass, more than that of Antimony, Silver and Bismuth.

Element Lead, Pb, Poor Metal. Calcium, which exhibits relations of isomorphism in both directions, stands in the middle. On the other hand, lead is decidedly a heavy metal, and forms an insoluble, dark-coloured sulphur compound. The combining weight of lead has been determined by the conversion of the metal into the oxide, and vice versa. It has been found to be Pb. Greeks called it molybdos; the same n.

In its chemical relations mercury, or Hydrargyrum, is most nearly allied to copper, since it forms, like it, two elementary ions, a monovalent and a divalent, which in many respects also are similar to those of copper. With cadmium it shares the tendency to form slightly dissociated halogen compounds of the divalent series. Pneumatic trough for the investigation of gases at once led to the discovery of a series of hitherto unknown substances.

Element Tin, Sn Stannum, Poor Metal. Has been used, since epochs of Homer and Moses. Alluvial aggradations are found much more often and may be processed much easier than other ores. Brythons were closely familiar with tin. As Cornwall slag hills testify.

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.