VII.—On the condition of the hydrogen occluded by palladium, as indicated by the specific heat of the charged metal
Journal of the Chemical Society (Resumed)
GRAHAM'S researches " on the relation of palladium to hydrogen " led to the conclusion that the absorbed hydrogen exhibits decided metallic properties, and that the palladium with its occluded hydrogen is an alloy. As the specific heats of alloys always approximate to the means of those of their constituents (Kopp), it was thought that by determining the specific heat of the alloy and that of the original palladium, the specific heat of the occluded hydrogen could be calculated; it was further
... nticipated that this value would be somewhere near 6.6, in accordance with D u 1 on g and Petit's well-known generalisation. Palladium mire and foil, also palladium-gold alloy (containing 20 per cent. of gold) in the form of wire, were charged with hydrogen by making the metal to be charged the negative pole of a voltaic battery electrolysing acidulated water, The charged metal was well washed with water and then with alcohol, and then heated to a temperature close upon 100" ; when the palladium was completely saturated with hydrogen, a slight disengagement of gas took place at loo", but this was observed only when the occluded gas exceeded 60 C.C. at 0" and 760 mm. per gram of palladium. In the few experiments in which a further disengagement took place on repeatedly heating to 100" in the courae oE the determiaations, the small quantity of gas thus expelled waa collected and allowed for. The specific heat between 15Oand 100" of the charged palladium was then estimated by plunging the substance heated to near 100" into a calorimeter, the results being calculated by means of the followwhere s = the specific heat of the charged metal, W =r. the water-equivalent of the calorimeter in grams, w = the weight of palladium, w' = the weight of hydrogen occluded, T = the initial temperature of the charged palladium, t = the initial temperature of the calorimeter, f' = the final temperature of tbe calorimeter, corrected, when PecessiFrJT, for atmospheric influences, radiation, &c.