482 ME. T. GEAHAM ON THE AB80EPTI0N AND 



Copper. 



The power to occlude gases appears not to be confined to palladium and platinum 

 among the metals. The exact exj>eriments of M, Dumas, by which the atomic weights 

 of the leading elements were definitely settled, afford an indication of the absorption of 

 hydrogen gas by spongy metallic copper reduced from the oxide, sufficient to affect the 

 weight of the metal to the extent of about 3 parts in 100,000*. 



1. With the view of applying the method of extracting gas followed in the treatment 

 of the preceding metals, so much oxide of copper was reduced by hydrogen as was cal- 

 culated to yield 50 grms. of metallic copper. The reduced metal was again heated to 

 redness and slowly cooled in a stream of dry hydrogen. After free exposure to the air 

 for a few minutes, the metal was now submitted, at a red heat, to the action of the 

 Sprengel pump. It then gave off in one hour 3'35 cub. centims. of gas, measured cold, 

 which appeared to be pure hydrogen (the explosion with oxygen indicated 3-4 hydrogen). 

 Taking the specific gravity of copper at 8-85, 60 grms. of that metal would be 5*65 cub. 

 centims. in volume, and the result is that 



1 vol. reduced copper sponge occludes 0'6 vol. hydrogen. 



Hydrogen being about 12,000 times as light as copper (at 15°), 1 part of gas by weight 

 has been taken up by 20,000 parts of metal. 



2. The same weight and volume of fine copper, in the form of wire, thoroughly 

 cleaned, was exposed to hydrogen at a red heat, and then submitted to exhaustion for 

 one hour. It gave 2 "6 cub. centims. gas, of which 2 cub. centims. were hydrogen, and 

 the remaining 0'6 principally carbonic oxide. It may be represented that 



1 vol. wrought copper occludes 0'306 vol. hydrogen. 



Where a metal, such as wrought copper, may contain small quantities of carbon and 

 oxygen, an obvious cause will exist for the production and evolution of carbonic oxide 

 under the influence of heat. Gas so generated appears to be added to the occluded 

 hydrogen when extricated, in the last experiment. 



Gold. 



1. A quantity of gold was precipitated from the assay cornettes used below by means 

 of oxalic acid. The gold weighed 93*3 grms., with a volume of 4-83 cub. centims., 

 taking the specific gravity of the metal as 19*31. Exhausted at a red heat without any 

 further treatment, the reduced gold yielded 3*4 cub. centims. of gas, which may therefore 

 be supposed to be gas usually present in gold reduced in the manner described. This 

 is 0704 vol. of the gold. The occluded gas in precipitated gold gave to analysis 



* Annales de Chimie et de Physique, 3 s^r. t. viii. p. 205. The observatioiis of M. Melseks show that 240 gnns. 

 of copper may fix about 0-007 grm. of hydrogen, most being fixed when the oxide of copper is reduced by 

 hydrogen at a low temperature. In the subsequent oxidation of the copper the gas does not come out suddenly, 

 but in a gradual manner. 



