DIALYTIC SEPABATION OF GASES BY COLLOID SEPTA. 429 



Of Ether 1-7 part. 



Of Acetone (0-794) 0-54 „ 



Of Glycerine 4 5 parts. 



Of Benzol 3'5 „ 



Of Oil of sweet almonds . . . 18'1 



Of Castor-oil ....... 10-2 



j> 



»» 



The superior penetrativeness of alcohol over water is well marked ; capillary action 

 appears to merge into a chemical affinity. Liquid hydrogen would also appear as highly 

 absorbable by palladium-foil. It would appear also to be separable from other gases 

 (or liquids), as alcohol is from water, by the palladium-pores. 



Alloy of 5 palladium and 4 silver. — The power to absorb hydrogen appears to extend 

 to this alloy of palladium. A plate of the alloy, about 180 millims. in length, 31 millims. 

 in width, and weighing 74*3 grms., was bent, so as to be able to enter a wide porcelain 

 tube that could be exhausted of air when required. The volume of the palladium alloy 

 was 6-21 cub. centims. The plate of metal being placed in the porcelain tube, had 

 hydrogen gas passed over it at a low red heat for one hour, and was then allowed to cool 

 slowly in the same gas. Taken out and examined, the metal was not visibly altered. 

 For the extrication of gas the metal was distilled in the porcelain tube heated by jets of 

 gas, and connected with the Sprengel pump, as usual. In seven minutes after the gas- 

 furnace was lit, 24 cub. centims. of gas came off; in ten minutes more, 80"71 cub. 

 centims. ; and in seventy-five minutes more, 36*75 cub. centims., making altogether 

 141'46 cub. centims. Of this gas 127"74 cub. centims. proved to be hydrogen, the 

 remainder being nitrogen, derived, no doubt, from the large imperfectly exhausted 

 porcelain tube. The palladium alloy, in the form of a thick plate, appears therefore 

 to have held 



20-5 vols, hydrogen, measured at 18°-2 and barom. 756 millims. 



This alloy of palladium becomes crystalline by heating, and appears to lose much of 

 its absorbent power at the same time. 



The conclusion, then, is that welded palladium, in the condition of thin foil, readily 

 absorbs hydrogen, to the extent of upwards of 600 times the volume of the metal at a 

 temperature under the boiling-point of water, upwards of 500 volumes at 245°, and less 

 at higher temperatures, the metal being always surrounded by hydrogen under atmo- 

 spheric pressure. Hydrogen is also largely absorbed, although less constantly, at 

 ordinary temperatures. On the other hand, palladium already fully charged with 

 hydrogen at or under 100°, and under the pressure of the atmosphere, begins to give 

 out gas when exposed either to atmospheric air or to a vacuum at the original tempe- 

 rature of absorption ; and the gas is freely discharged at 200° C. 



It is probable that hydrogen enters palladium in the physical condition of liquid, 

 whether the phenomenon proves to be analogous to the imbibition of ether, chloroform, 

 and such solvents by the coUoid india-rubber, or whether a certain porosity of structure 

 in the palladium is required. The porosity of the metal is supposed to be of that high 



