446 On the Fire-damp of Coal-Mi?ies, and on Methods 



The fire-damp is produced in small quantities in coal mines, 

 during the common process of working. 



The Rev. Mr. Hodgson informed me, that on pounding some 

 common Newcastle coal fresh from the mine in a cask fmnished 

 with a small aperture, the gas from the aperture was inflam- 

 mable. And on breaking some large lumps of coal under water, 

 I ascertained that they gave off inflammable gas*. Gas is like- 

 wise disengaged from bituminous schist, when it is worked. 



The great sources of the fire-damp in mines are, however, 

 what are called blowers, or fissures in the broken strata, near 

 dykes, from which currents of fire-damp issue in considerable 

 quantity, and sometimes for a long course of yearsf. When 

 old workings are broken into, likewise, they are often found 

 filled Avith fire-damp ; and the deeper the mine the more com- 

 mon in general is this substance. 



1 have analysed several specimens of the fire-damp in the 

 laboratory of the Royal Institution ; the pure inflammable part 

 was the same in all of them, but it was sometimes mixed with 

 small quantities of atmospherical air, and in some instances 

 with azote and carbonic acid. 



Of six specimens collected by Mr. Dunn from a blower in the 

 Hepburn Colliery, by emptying bottles of water close to it, the 

 purest contained ~ ^''^y ^'f atmospherical air, with no other 

 contamination, and the most impure contained ■f\ of atmo- 

 spherical air ; so that this air was probably derived from the cir- 

 cumambient air of the mine. The weight of the purest speci 

 men was for 100 cubical inches 19-5 grains. 



* This is probably owing to the coal strata having been formed under a 

 pressure greater than tliut of the atiuospliere, so tliat they >i\ve off elastic 

 fluid when they are exposed to the free atmosphere: and probably coals 

 containing animal remains evolve not only the fiie-damp, but likewise 

 a-zotc and carbonic acid, as in the instance of the gas sent by Dr. Clanny. 



In the Apennines, near Pietra Mala, I examined a fire produced by 

 gaseous matter, constantly disengaj;ed from a scliist stratum: and from the 

 results of the combustion, I have no doubt but that it was pure fire-damp. 

 Mr. M. Faraday, who accompanied me, and assisted mc in my chemical 

 experiments, in my jom'ney, collected some gas from a cavity m the earth 

 about a mile from Pietra Mala, then filled with water, and which, from 

 the quantity of gas disengaged, is called Aqua Buja. I analysed it in the 

 Grand Duke's laboratory at Florence, and found that it was pure light 

 hydro-carbonate, requiring two volumes of oxygen for its combustion, and 

 producing a volume of carbonic acid gas. 



It it very probable that tiiese gases are disengaged from coal strata he- 

 'Vjath the surface, or from bituminous schist above coal ; and at some fu- 

 ture period new sources of riches may be opened to Tuscany from this 

 iuvaluable mineral treasure, the use. of which in this country has supplied 

 such extraordinary resources to industry. 



f Sir James Lowiher found a uniform current produced in one of his 

 ttiinei fur two years cjiud nine nionthi, Phil. Trans, vol. xxxviii. p. 112- 



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