518 Mr. T. Graham on the Absorption and 



usual way, the palladium was found to have absorbed, at 100°, 



347*7 vols, of hydrogen measured at 18°'2 C. and barom. 

 756 millims. 



5. So large an absorption of hydrogen should increase the 

 weight of the palladium sensibly, notwithstanding the lightness 

 of the gas. One litre, or 1000 cub. centims., of hydrogen at 

 0° C. and 760 millims. weighs 0*0896 grm. Of new palladium- 

 foil, believed to be horn fused metal, 5*9516 grms. increased to 

 5*9542, or by 0*0026 grm., when the metal was charged with 

 hydrogen at 100° for four hours. This amounts to only 29*01 

 cub. centims. of hydrogen at 0° C. and 760 millims. barom. 

 The gas actually extracted afterwards from the.palladium did not 

 exceed 34*2 cub. centims. at 19° C, and barom. 758 millims., 

 equivalent to 31*84 cub, centims. at 0° C. and 760 millims. ba- 

 rom. The whole gas extricated (68 vols.) seems unusually small, 

 but it corresponds closely enough with the volume calculated 

 from the increase of the palladium in weight. An inferior ab- 

 sorbing-power for hydrogen appears to be connected in both pla- 

 tinum and palladium with the fusion of the metal. 



6. A portion of similar palladium -foil, charged with hydrogen, 

 was found to have its gas reduced from 20*7 to 16*2 cub. cen- 

 tims. after exposure to the air for forty-two hours. The liquid 

 hydrogen, whether held by the substance or in the pores of the 

 metal, appears therefore to evaporate slowly at the temperature 

 of the atmosphere, therm. 19°, barom. 752 millims. 



7. Spongy palladium, from the ignition of the cyanide, being 

 heated in hydrogen at 200°, and allowed to cool slowly in the 

 same gas for four hours, the metal was found to have taken up 

 686 vols, of hydrogen. 



Treated in a similar manner with air, spongy palladium exhi- 

 bited no absorbing-power for oxygen or nitrogen. 



Hydrogen, condensed either in the palladium sponge or foil, 

 was observed to have its chemical affinities enhanced. The pal- 

 ladium being placed in dilute solutions of the following substances 

 for twenty-four hours in the dark at the ordinary temperature, 

 the action of the hydrogen became manifest. 



Persalt of iron became protosalt. 



Ferricyanide of potassium became ferrocyanide. 



Chlorine-water became hydrochloric acid. 



Iodine-water became hydriodic acid*. 



Apart from hydrogen, the palladium sponge exhibits a power 



* The power of platinum-black charged with hydrogen to communicate 

 the latter element to organic compounds has lately been observed by M. 

 P. de Wilde, following Dr. Debus. — Bulletin de la Societe Chimique, March 

 1866. 



