504 



Mr. T. Graham on Hijdrogenium. [June 17, 



1*902 on 100, and a cubic expansion of 5*81 on 100. The volume of 

 hydrogen gas extracted was 188*8 cub. centims., of which the weight is 

 0*016916 grm. The volume of the hydrogenium was 0*02365 cub. centim., 

 that of the palladium-gold alloy being 0*40/1 cub. centim. Hence the 

 density of the hydrogenium is 0*715. 



In a third experiment made on a shorter length of the same wire, 

 namely 241*2 millims., the amount of gas occluded was very similar, namely 

 468 volumes, and was not increased by protracting the exposure of the 

 wire for the long period of twenty hours. There can be little doubt, then, of 

 the uniformity of the hydrogenium combination, the volume of gas occluded 

 in the three experiments being 464*2, 463*7, and 468 volumes. The linear 

 expansion was 1*9 on 100 in the third experiment, and therefore similar 

 also to the preceding experiments. 



The hydrogenium may be supposed to be in direct combination with the 

 palladium only, as gold by itself shows no attraction for the former element. 

 In the first experiment the hydrogenium is in the proportion of 0*3151 to 

 100 palladium and gold together. This gives 0*3939 hydrogenium to 100 

 palladium ; while a whole equivalent of hydrogenium is 0*939 to 100 pal- 

 ladium*. The hydrogenium found is by calculation 0*4195 equivalent, 

 or 1 equivalent hydrogenium to 2*383 equivalents palladium, which comes 

 nearer to 2 equivalents of the former with 5 of the latter than to any other 

 proportion. 



To ascertain the smallest proportion of gold which prevents retraction, 

 an alloy was made by fusing 7 parts of that metal with 93 parts of palla- 

 dium, which had a specific gravity of 13*05. The button was rolled into 

 a thin strip and charged with hydrogen by the wet method. An occlusion 

 of 585*44 volumes of gas took place, with a linear expansion of 1*7 on 

 100. A retraction followed to nearly the same extent on afterwards ex- 

 pelling 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 retraction on expelling the gas afterwards was extremely slight. To 

 nullify the retraction of the palladium, about 10 per cent, of gold appears 

 therefore to be required in the alloy. 



Another alloy of palladium of sp. gr. 13*1, and containing 14*79 per 

 cent, of gold, underwent no retraction on losing hydrogen, as already 

 stated. 



The presence of so much gold in the alloy as half its weight did no 

 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. 



3. Palladium, Silver, and Hydrogenium. — The occluding power of pal- 

 ladium appeared to be entirely lost when that metal was alloyed with much 

 more than its own weight of any fixed metal. Palladium alloys con- 

 * H=l; Pd = 106-5. 



