502 



Mr. T. Graham on Hydrogenium. 



[June 17, 



1. Palladium, Platinum, and Hydrogenium. — 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 surface in the 

 acid fluid of the galvanometer, with great avidity. 



A wire 601*845 millims. in length (23*69 inches) was increased to 

 618*288 millims., on occluding 701*9 volumes of hydrogen gas measured 

 at 0°C. and 0*76 barom. This is a linear elongation of 16*443 millims. 

 (0*6472 inch), or 2*732 on a length of 100. It corresponds with a cubic 

 expansion of 8*423 volumes on 100 volumes ; and the product may be 

 represented — 



In volume. 



Fixed metals 100*000 or 92*225 



Hydrogenium 8*423 or 7'775 



108*423 or 100*000 



The elements for the calculation of the density of hydrogenium are the 

 following, the assumption being made as formerly, that the metals are 

 united without condensation : — 



Original weight of the wire 4*722 grms. 

 Original volume of the wire 0*373 cub. centim. 

 Volume of the hydrogen extracted 264*5 cub. centims. 

 Weight of the hydrogen extracted, by calculation, 0*0237 grm. 



The volume of the hydrogenium will be to the volume of the wire 

 (0*373 cub. centim.) as 100 is to 8*423— that is, 0*03141 cub. centim. 

 Finally, dividing the weight of the hydrogenium by its bulk, 0*0237 by 

 0*03141, the density of hydrogenium is found to be 0*7545. 



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 palladium, 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. It now ap- 

 pears clear that the retraction of pure palladium must occur on the first 

 entrance of hydrogen into the metal. The elongation of the wire due to 

 the hydrogenium is negatived thereby to the extent of about one half, 

 and the apparent bulk of the hydrogenium is reduced to the same extent. 

 Hydrogenium came in consequence to be represented of double its true 

 density. 



The compound alloy returns to its original density (12*64) upon the 

 expulsion of the hydrogen, showing that hydrogen leaves without pro- 

 ducing porosity in the metal. No absorptive power for vapours, like 

 that of charcoal, was acquired. 



A wire of the present alloy, and another of pure palladium, were charged 



