III. On the occlusion of hydrogen and oxygen by palladium

Abstract

Since the discovery by Graham (‘Phil. Trans.,' 1866, p. 399, also ‘Graham’s Researches,’ p. 235), that palladium possesses the property of occluding or absorbing large quantities of hydrogen, chemical literature has been enriched by various con­tributions to our knowledge of this interesting phenomenon. To mention only a few of these, some of which will later on be considered in detail, we have the results of investigations on the change of volume undergone by palladium on the occlusion of hydrogen, the density of the occluded hydrogen, the heat changes which take place, and the pressure of “palladium hydrogen” at different temperatures, &c. The solution of hydrogen in, or the combination of hydrogen with, palladium, which we may be permitted provisionally to term palladium hydrogen, is now often used in laboratories as a convenient source of pure hydrogen; and finely divided palladium, on account of the facility with which it absorbs hydrogen, is also extensively employed in gas analysis. Hydrogen, occluded by palladium, may con­veniently be weighed as palladium hydrogen, and recourse was had by Keiser (‘Am. Chem. Journ.,' vol. 10, p. 249) to this method of weighing hydrogen in one of the most delicate of chemical operations, viz., that of atomic weight determination.