The concepts of ″carbide-forming element″ and ″whitening element″ are not equivalent in the metallography of cast iron. With a decrease in the solubility of carbide-forming elements in cementite their whitening effect on the structure of cast iron decreases. The further an element is located from iron in the periodic table leftward along the period or downward along the subgroup, the lower its solubility in cementite and the weaker its whitening effect. The precipitation of special carbides in cast iron can even have a graphitizing effect which has thermodynamic and kinetic components.