Occlusion of Gases by Palladium

Palladium possesses to a remarkable degree the power of absorbing or occluding certain gases, the actual extent of the absorption depending upon the physical condition of the metal. The term occlusion was first used by Graham in 1866 to signify the absorption or shutting up of gases in solid substances.

Of all gases the most readily absorbed is hydrogen, and to this full reference is made below.

Both oxygen and carbon monoxide are absorbed by palladium black, the former presumably converting the metal into the monoxide, PdO, whilst the latter yields a curious substance which begins to decompose at 250° C.

Helium is not readily absorbed by palladium, a fact that enables admixed hydrogen to be readily separated from it.