THE FIRE-DAMP'S FAMILY CIRCLE. 191 



nature, and believing that the gases evolved during some ope- 

 rations of metallic solution were also sulphureous, he arrived 

 at the conclusion that hydrogen (of course, unknown to him 

 as such) was similar to fire-damp, if not identical with it. 

 Alluding to the sulphureous fumes which he assumed to be 

 evolved by metals under particular circumstances, he goes 

 on to say that of these fumes ' iron emits a great quantity 

 whilst dissolving in oil of vitriol, which are very inflammable 

 and not easily condensed. 



6 These fumes I collected into a bladder with the desired 

 success ; and having produced before the society two bladders 

 of this fictitious air, at the same time that Sir James Louther 

 was pleased to make a trial of his, they both exhibited the 

 same phenomena.' 



From this account it will be seen that Mr. Maud un- 

 questionably generated hydrogen, collected it, and operated 

 upon it. He imagined, however, that it came from the iron 

 employed in the experiment, or the sulphur united with the 

 iron, and believed it to possess a sulphureous nature. Indeed, 

 the notion that the fire-damp was either a kind of sulphur or 

 in some way allied to sulphur, continued to be a tenet held 

 by philosophers of the last century not less firmly than it is 

 held by working coal-miners of the present day. 



As the elements of the ancients were four fire, air, earth, 

 and water so the elements of the alchemists were three 

 salt, sulphur, and mercury. Of these, sulphur was the one 

 assumed to be concerned in all that related to combustion or 

 combustibility. Thus it is easy to perceive whence *the notion 

 of fire-damp being sulphureous originated, and wherefore the 

 term 4 sulphur' is conventionally applied in miners' language 

 to fire-damp at the present time. 



Two years later than the experiment just described, and 

 which proved the similarity between fire-damp and hydrogen 

 gas, a very demonstrative course of four experiments for 

 the time, very remarkable ones was performed by Dr. Des- 



