1869.] 



Mr. T. Graham on Hydrogenium. 



503 



with hydrogen, and the diameters of both measured by a micrometer. The 

 wire of alloy increased sensibly more in thickness than the pure palladium, 

 about twice as much ; the reason is, that the latter while expanding re- 

 tracts in length at the same time. The expansion of both wires may be 

 familiarly compared to the enlargement of the body of a leech on absorbing 

 blood. The enlargement is uniform in all dimensions with the palladium - 

 platinum alloy ; the leech becomes larger, but remains symmetrical. But 

 the retraction in the pure palladium wire has its analogy in a muscular con- 

 traction of the leech, by which its body becomes shorter but thicker in a 

 corresponding measure. 



The same wire of palladium and platinum charged a second time with 

 hydrogen, underwent an increase in length from 601*845 to 618*2, or 

 sensibly the same as before. The gas measured 258*0 cub. centims., or 

 619*6 times the volume of the wire. The product may be represented as 

 consisting of 



By volume. 



Fixed metals 92*272 



Hydrogenium 7*728 



100*000 



The density of hydrogenium deducible from this experiment is 0*7401. 

 The mean of the two experiments is 0*7473. 



2. Palladium, Gold, and Hydrogenium. — Palladium fused with gold 

 formed a malleable alloy, consisting of 75*21 parts of the former and 24*79 

 parts of the latter, of a white colour, which could be drawn into wire. 

 Its specific gravity was 13*1. Of this wire 601*85 millims. occluded 464*2 

 volumes of hydrogen with an increase in length of 11*5 millims. This 

 is a linear elongation of 1*91 on 100, and a cubic expansion of 5*84 on 

 100. The resulting composition was therefore as follows : — 



In volume. 



Alloy of palladium and gold .... 100 'or 94*48 

 Hydrogenium 5*84 or 5*52 



105*84 100*00 



The weight of the wire was 5*334 grms. 



The volume of the wire was 0*4071 cub. centim. 



The volume of hydrogen extracted, 189*0 cub. centims. 



The weight of the hydrogen, 0*01693 grm. 



The volume of the hydrogenium, 0*02378 cub. centim. 



Consequently the density of the hydrogenium is 0*711. 



The wire returned to its original length after the extraction of the hy- 

 drogen, and there was no retraction. 



The results of a second experiment on the same wire were almost iden- 

 tical with the preceding. 



The elongation on 601*85 millims, of wire was 11*45 millims., with the 

 occlusion of 463*7 volumes of hydrogen. This is a linear expansion of 



VOL. XVII. 2 P 



