Abstract
Metals which absorb hydrogen can be classified into three groups: (a) group of salt-type-hydride forming metals. where hydrogen atoms are located substitutionally in the lattice, thas absorbing exothermically large quantity of hydrogen: NaH, CaH2…, (b) group of true solution of hydrogen in metals, so-called “poor absorbers”, where hydrogen atoms are located interstitially in the lattice,thus absorbing endothermically only a small quantity of hydrogen: H in Fe, Ni, Cu…, (c) intermediate group of the above both groups, so-called “good absorbers” mixtures of hydride and interstitial solutions, absorbing apparently exothermically mediate quantity of hydrogen: Pd, Ti, U…. The authors have found that the heat of solution of hydrogen of a- or b-group metals is proportional or in inverse ratio respectively to the ionization energy of the metals. These facts, to-gether with other phenomena, may be cited as proofs of the negative or positive character of the dissolved hydrogen atom in the metals.
