526 Mr. T. Graham on the Absorption and 



The gas consisted of 



2*4 cub. centims. Carbonic acid. 

 0*6 „ „ Carbonic oxide. 



Silver wire therefore appeared to hold occluded 0*289 volume 

 of gas, principally carbonic acid. There is reason, however, to 

 suppose that the occluded gas may really be oxygen, and that 

 the latter was converted into carbonic acid at the temperature 

 of extrication, by a trace of carbon existing in the fine silver. 



2. The same quantity of silver wire was now charged with 

 hydrogen, by being heated to redness and afterwards cooled 

 slowly in that gas. The gas extricated amounted to 



2*3 cub. centims. in forty-five minutes. 

 0*2 „ „ in fifteen minutes. 



2*5 „ „ in one hour. 



The gas consisted of 



2*2 cub. centims. Hydrogen. 

 0-3 „ „ Nitrogen, &c. 



2*5 



The fine silver had therefore occluded 0*211 volume of hy- 

 drogen. The metal acquired a beautiful frosted appearance on the 

 surface ; and by repeated heating it became highly crystalline and 

 brittle. 



3. The same portion of silver was now charged with oxygen. 

 The occluded gas given off amounted to 



7*5 cub. centims. in thirty minutes. 



0*3 33 „ 33 



7*8 „ in one hour. 



The gas consisted of 



7*6 cub. centims. Oxygen. 



0*2 „ Nitrogen, Sec. 



7^ 



The silver therefore held occluded 0*745 volume of oxygen. 

 This gas, like the hydrogen in platinum, was permanently fixed 

 in the metal at all temperatures below an incipient red heat. It 

 did not tarnish the bright metallic surface of the silver, or pro- 

 duce any appearance suggestive of the oxidation of a metal. 



4. The same portion of silver, after being dissolved in acid, 

 precipitated as chloride, and reduced again, was exposed to atmo- 

 spheric air at a red heat, and afterwards exhausted. The gas 



