35S Accident at Felling Colliery, [May^i 



men . are at work — each part of the mine will be uniformly 

 wholesome ; but when obstructions occur, and are not speedily 

 removed ; when the fire in the furnace shaft is neglected ; or 

 when care has not been taken to place the stoppings and trap- 

 doors in proper places, or the trap-doors are carelessly left open, 

 or stoppings fall down,-— in all these cases accumulations of fire-- 

 damp^ (called sty the by the colliers), immediately commence in 



* Note by the Editor. — What is called fire-damp in coal- 

 mines is the carhiireted hydrogen gas of chemists, as I have ascer- 

 tained by direct experiments. It is composed of 



Carbon .72 



' Hydrogen 28 



100 



or of two atoms of hydrogen, and one of carbon. I have been 

 informed that it always exists in coal-mines, mixed with carbonic 

 acid ; and all the specimens of it which I have ever procured for the 



furpose of examination, contained a mixture of that gas. Hence 

 conceive that fire-damp is formed by the action of coal upon 

 water. The water is decomposed, two atoms at once. All the 

 oxygen combines with carbon, and forms carbonic acid ; while all 

 the hydrogen unites likewise with carbon, and forms carbureted 

 hydrogen, or fire-damp. 



I never could succeed in making any mixture of fire-damp and 

 common air explode. It only burnt rapidly, with a blue flame, and 

 little noise; but when mixed with oxygen gas in the proper proper^ 

 tion it explodes with great violence. Suppose we take 100 measures 

 of pure carbureted hydrogen gas, it v^^ill not explode unless the 

 oxygen present amount to 105 measures, and it ceases to explode 

 whenever the oxygen amounts to more than 227 measures. Hence 

 it would seem that whenever the fire-damp in mines amounts to ^Vth 

 of the bulk of common air present, it will be apt to explode with a 

 candle; and that whenever it exceeds ^th of the air, it will no 

 longer be capable of exploding. All proportions between i and 

 will explode. 



We are not acquainted with any means of preventing the forma- 

 tion of this gas ; but it certainly might be prevented from accumu- 

 lating, by ventilating the mine properly. If the usual method of 

 fires, &c. be insufficient, nothing would be easier than to pump the 

 air out of the mine, by means of an engine; and this would secure 

 a perfect ventilation at ail times, unless we suppose the workmen 

 culpably negligent. I would advise the overseers of coal-mines, 

 where fire-damp exist?, to learn the method of analysing the air 

 of the mine, in order to know when the fire-damp approaches to 

 yVth of the air, that they might be aware of their danger, and 

 have it in their power to take the requisite precautions to prevent 

 it. The process to be followed is very simple : it would not require 

 ^ny expensive apparatus, and might be perfectly learned in two ov 



