1814.] Prevention of Explosion in Coal Mines. 435 



of chemical science. Whenever vegetable charcoal is left in con- 

 tact with water at a certain temperature, the water is decomposed 

 and two new gases evolved, namely carbureted hi/drocien and car- 

 bonic acid. This h;ippens during summer in all marshes and 

 ditches, as is well known to every chemist. • It is by this process of 

 nature alone that pure carbureted hydrogen can be obtamed for 

 chemical examin'ition. I conceive a similar process to be gomg on 

 in coal pits, where the temperature is always high, and where 

 abundance of coal is always lying in contact with water. I do not 

 "ee how the presence of pyrites in coal should occasion or mcrease 

 the evolution of carbured hydrogen, which there is every reason to 

 consider as the only Jire damp that ever makes its appearance in 



coal mines. , 



I wish the proprietors of coal mines would turn their attention to 

 some circumstances, which if duly attended to would enable them 

 completely to put an end to the disasterous effects of explosions of 

 fire damp in their mines. These circumstances are the following : 



1. Explosions of fire damp are entirt-ly confined to deep coal niuies,^ 

 and never happen in those at no great distance from the surface of 

 the ground. Thus nobody ever heard of such explosions in the 

 Deighbourhood of Edinburgh or Glasgow ; but about Borrowstoness, 

 where the mines are deep, they occur as well as in England. 



2. The specific gravity of carbureted hydrogen gas is only 0-555, 

 or a very little more than one half of the specific gravity of com- 

 mon air. 3. If you let go ever so much carbureted hydrogen gas 

 in a room with an aperture at the roof, and examine the air of the 

 room half an hour after, no traces of the carbureted hydrogen will 

 be detected. 4. Carbureted hydrogen will not explode unless it 

 amount to yUth of the bulk of the common air with which it is 



mixed. The unavoidable conclusion from these facts is, that if 



the fire damp accumulate in coal mines so as to explode, it is only 

 because circumstances prevent it from making its escape with sufli- 

 cient rapidity. Hence it follows, that the defect lies in the mode 

 employed at^resent to ventilate coal mines ; and tliat if the mines 

 were ventilated according to the well known principles of hydrau- 

 lics, no explosions ever would take place. 



To prevent the evolution of fire damp I conceive to be mi-.^ 

 possible ; to attempt to destroy it when formed, as has been some- 

 times proposed, is quite absurd ; but allow it to make its escapfe 

 from the mine without obstruction, and it will occasion no incon- 

 rcnicncc whatever. 



2K 2 



