368 



Dr. J. W. Mallet on the Gases occluded in [May 30, 



Other gases were tested for, but none could be found ; no free oxygen 

 could be detected, nor any compound of carbon and hydrogen. 



From these figures it appears that hydrogen maintains about the same 

 proportion to the other gases in A and B, but diminishes largely in C, 

 that carbonic oxide increases in amount in B as compared with A, but re- 

 mains about the same in relative amount in C, that carbonic anhydride 

 diminishes throughout the whole continuance of the experiment, and that 

 nitrogen falls off in B as compared with A, but largely increases again 

 in C. 



Contrasting the results with those of Graham, and noticing first the total 

 volume of gas obtained from the iron, it becomes necessary to reduce this 

 volume to the same standards of pressure and temperature employed by 

 him. In the paper read before the Royal Society, as reported in its ' Pro^ 

 ceedings,' I find no statement in regard to such standards; but, supposing 

 it probable that the barometer at 30 inches and thermometer at 60° F. 

 were referred to, I have calculated the volume of gas obtained in all from 

 1 5 " 8 7 cub. centims. of iron as equivalent under these conditions of pressure 

 and temperature to 50 40 cub. centims., or 3*17 times the volume of the 

 metal. This is a somewhat larger quantity than that of Graham, namely 

 2'85 times the volume of the Lenarto iron used ; but the time of heating 

 was longer in the experiment now described, and the temperature attained 

 probably much higher. 



As to the nature and relative amount of the constituent gases, the results 

 differ very noticeably from those of Graham, as is evident when the 

 figures of the two analyses are placed side by side : — 



-r , . Augusta Co., 



Lenarto iron. b . . . ' 



Virginia iron. 



Hydrogen 85-68 35-83 



Carbonic oxide 4 '46 38'33 



Carbonic anhydride 9*75 



Nitrogen 9'86 16-09 



100*00 100-00 



The gases obtained in the experiment now in question agree more nearly 

 with those of common wrought iron (clean horseshoe-nails) as found by 

 Graham*, viz. in the first portion collected,— 



Hydrogen 35*0 



Carbonic oxide < . 50'3 



Carbonic anhydride 7*7 



Nitrogen. 7*0 



100-0 



and the conclusion arrived at by him, that " the predominance of carbonic 

 oxide in its occluded gases appears to attest the telluric origin of iron," 



* Lod tit* 



