1869.] 



Mr. T. Graham on Hydrogenium. 



505 



taining 80, 75, and 70 per cent, of silver occluded no hydrogen what- 

 ever. 



With about 50 per cent, of silver, palladium rolled into a thin strip oc- 

 cluded 400*6 volumes of hydrogen. It expanded 1*64 part in 100 in 

 length, and returned to its original dimensions without retraction upon the 

 expulsion of the gas. The specific gravity of this silver-palladium alloy 

 was 11*8; the density of the hydrogenium 0*727. 



An alloy which was formed of 66 parts of palladium and 34 parts of 

 silver had the specific gravity 11*45. It was drawn into wire and found 

 to absorb 511*37 volumes of hydrogen. The length of the wire increased 

 from 609*601 to 619*532 millims. This is a linear elongation of 1*629 on 

 100, or cubic expansion of 4*97 on 100. The weight of the wire was 

 3*483 grms., its volume 0*3041 cub. centim. The absolute volume of 

 occluded hydrogen was 125*1 cub. centims., of which the weight is 

 0*01120896. The volume of the hydrogenium was 0*015105 cub. centim. 

 The resulting density of hydrogenium is 0*742. 



In a repetition of the experiment upon another portion of the same 

 wire, 407*7 volumes of hydrogen were occluded, and the wire increased 

 in length from 609*601 millims. to 619*44 millims. This is a linear ex- 

 pansion of 1*614 part on 100, and a cubic expansion of 4*92 on 100. 

 The absolute volume of hydrogen gas occluded was 124*0 cub. centims., and 

 its calculated weight 0*01111 grm. The volume of the hydrogenium 

 being 0*1496 cub. centim., the density of hydrogenium indicated is 0*741. 

 The two experiments are indeed almost identical. The wire returned 

 in both experiments to its original length exactly after the extraction of 

 the gas. 



4. Palladium, Nickel, and Hydrogenium. — The alloy, consisting of equal 

 parts of palladium and nickel, was white, hard, and readily extensible. Its 

 specific gravity was 11*22. This alloy occluded 69*76 volumes of hydro- 

 gen, with a linear expansion of 0*2 per cent. It suffered no retraction 

 below its normal length on the expulsion of the gas by heat. 



An alloy of equal parts of bismuth and palladium was a brittle mass that 

 did not admit of being rolled. It occluded no hydrogen, after exposure to 

 that gas as the negative electrode in an acid fluid for a period of 18 hours. 

 It seems probable that malleability and the colloid character, which are 

 wanting in this bismuth alloy, are essential to the occlusion of hydrogen by 

 a palladium alloy. 



An alloy of 1 part of copper and 6 parts of palladium proved moderately 

 extensible, but absorbed no sensible amount of hydrogen. The metallic 

 laminae which remain on digesting this alloy in hydrochloric acid, and 

 which were found by M. Debray to be a definite alloy of palladium and 

 copper (Pd Cu), exhibited no sensible occluding power. 



The conclusions suggested as to the density of hydrogenium, by the 

 compound with palladium alone and by the compounds with palladium 

 alloys, are as follows : — 



2 p 2 



