HYDROGENIUM. 



341 



its volume 0.126 cubic centim. The occluded 

 hydrogen measured 120.5 cubic centims. ; the 

 weight of the same would be Q.0108 grm., 

 and the volume of the hydrogenium 0.012382 

 cubic centims., and its density therefore 0.872, 

 which is a near approach to the preceding 

 result of 0.854. Calculated on the old method, 

 the last experiment would give a density of 

 1.758. 



Mr. Graham presented the results of ex- 

 periments upon the occlusion of hydrogen by 

 the alloy of palladium with various metals. 

 He had first ascertained that palladium alloyed 

 with silver continued to occlude hydrogen, and 

 he afterward proved that this property be- 

 longs generally to the palladium alloys when 

 the second metal does not much exceed one half 

 of the mixture. The alloys are all enlarged in 

 dimensions, when they acquire hydrogenium. 

 In conducting the experiments, the alloy of 

 palladium with platinum, gold, etc., was made 

 into wire or a thin ribbon, and the elongation 

 caused by the addition of hydrogenium meas- 

 ured on a graduated scale as in the earlier 

 experiments ; the results appear in the follow- 

 ing summary : 



Palladium was fused with platinum, a metal of its 

 own class, and gave an alloy consisting, according to 

 analysis, of 76.03 parts of the former, and 23.97 parts 

 of the latter. This alloy was very malleable and 

 ductile. Its specific gravity was 12.64. Like pure 

 palladium, it absorbed hydrogen, evolved on its sur- 

 face in the acid fluid of the galvanometer, with great 

 avidity. A wire 601.845 m. m. in length (23.69 inches) 

 was increased to 618.288 m.m., on occluding 701.9 

 volumes of hydrogen gas. On expelling all hydrogen 

 from the wire at a red heat, the latter returned to its 

 first dimensions as exactly as could be measured. 

 The platinum present appears to sustain the palla- 

 dium so that no retraction of that metal is allowed 

 to take place. This alloy, therefore, displays the 

 true increase of volume following the acquisition of 

 hydrogenium without the singular complication of 

 the retraction of the fixed metal. The compound 

 alloy returns to its original density (12.64) upon the 

 expulsion of the hydrogen, showing that hydrogen 

 leaves without producing porosity in the metal. 



Palladium, Gold, and Hydrogenium. Palladium. 

 fused with gold formed a malleable alloy, consist- 

 ing of 75.21 parts of the former, and 24.79 parts of 

 the latter, of a white color, and ductile. Its spe- 

 cific gravity was 18.1. A wire of this alloy, 601.85 

 m.m., lay occluded, 464.2 volumes of hydrogen, with 

 an increase in length of 11.5 m.m. The wire returned 

 to its original length after the extraction of the hy- 

 drogen, and there was no retraction. The hydro- 

 genium may be supposed to be in direct combination 

 with the palladium only, as gold by itself shows no 

 attraction for the former element. 



To ascertain the smallest proportion of gold which 

 prevents retraction, an alloy was made by fusing 

 seven parts of that metal with 93 parts of palladium 

 which had a specific gravity of 13.05. The button 

 was rolled into a thin strip and charged with hydro- 

 gen by the wet method. An occlusion of 585.44 vol- 

 umes of gas took place, with a linear expansion of 1.7 

 on 100. A retraction followed to nearly the same 

 extent on afterward expelling the hydrogen by heat. 



With another alloy, produced by fusing 10 of gold 

 with 90 of palladium, the occlusion of gas was 475 

 volumes, the linear expansion 1.65 on 100. The re- 

 traction on expelling the gas afterward was extremely 

 slight. To nullify the retraction of the palladium, 



about 10 per cent, of gold appears, therefore, to bo 

 required in the alloy. 



Another alloy of palladium of sp. gr. 13.1, and con- 

 taining 14.79 per cent, of gold, underwent no retrac- 

 tion on losing hydrogen, as already stated. 

 t The_presence of so much gold in the alloy as half 

 its weight did not materially reduce the occluding 

 power of the palladium. Such an alloy was capable 

 of holding 459. 9 times its volume of hydrogen with a 

 linear expansion of 1.67 per cent. 



Pallad^um, Silver, and Hydrogenium. The oc- 

 cluding power of palladium appeared to be entirelv 

 lost when that metal was alloyed with much more 

 than its own weight of any fixed metal. Palladium 

 alloys containing 80.75, and 70 per cent, of silver, oc- 

 cluded no hydrogen whatever. 



With about 50 per cent, of silver, palladium rolled 

 into a thin strip occluded 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. 



An alloy, which was formed of 66 parts of palla- 

 dium 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 m.m. 



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 m.m. to 619.44 m.m. The absolute volume 



O.L\J, .LUAJ.CGI.IJ ojLLuvob lucuticiti. j. iic wire returned, in 

 both experiments to its original length exactly after 

 the extraction of the gas. 



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 hydrogen, 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 lismufh 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 eighteen hours. It seems probable that malleability 

 and the colloid character, which are wanting in this 

 bismuth alloy, are essential to the occlusion of hydro- 

 gen by a palladium alloy. 



An alloy of one part of copper and six parts of pal- 

 ladium proved moderately extensible, but absorbed 

 no sensible amount of hydrogen. The metallic la- 

 minae which remain on digesting this alloy in hydro- 

 chloric acid, and which were found by M. Debray to 

 be a definite alloy of palladium and copper (PdCu) 

 exhibited no sensible occluding power. 



The following is a statement of the author's 

 conclusions as to the density of hydrogenium 

 observed in its compound with palladium, and 

 also with the palladium alloys : 



Density of 

 Hydrogenium observed. 



When united with palladium 0.8540 to 0.8720 



When united with palladium and platinum 0.7401 to 0.7545 

 When united with palladium and #old 0.7110 to 0.7150 

 When united with palladium and silver. . . 0.7270 to 0.7420 



He called attention to the fact that the re- 

 sults are most uniform with the compound 

 alloys, in which retraction is avoided, and they 

 lie between 0.7110 and 0.7545. Taking the 

 mean of these two numbers as the most legiti- 

 mate deduction from the experiments on the 

 compound alloys, Mr. Graham thought that 

 0.733 should be accepted provisionally as the 

 approximate density of hydrogenium. 



