Fire-Damp of the Newcastle Coal Mines. 439 



carburetted hydrogen. The only additional matters present 

 were nitrogen and oxygen ; the specimen collected in the most 

 favourable circumstances tor the exclusion of atmospheric air, 

 namely, that from the Bensham seam, still containing 0*6 per 

 cent, of oxygen. The gases also contained no carbonic acid. 



It is worthy of observation, that nothing oxidable at the 

 temperature of the air is found in a volatile state associated 

 with the perfect coal of the Newcastle beds. The remarkable 

 absence of oxidability in light carburetted hydrogen appears 

 to have preserved that alone of all the combustible gases ori- 

 ginally evolved in the formation of coal, and which are still 

 found accompanying the imperfect lignite coal of Germany, 

 of which the gas has been examined. This fact is of geological 

 interest, as it proves that an almost indefinitely protracted 

 oxidating action of the air must be taken into account in the 

 formation of coal; air finding a gradual access through the 

 thickest beds of superimposed strata, whether these strata be 

 in a dry state or humid. 



In regard to measures for preventing the explosion of the 

 gas in coal mines, and of mitigating the effects of such acci- 

 dents, I confine myself to two suggestions. The first has 

 reference to the length of time which the fire-damp, from its 

 lightness, continues near the roof, without mixing uniformly 

 with the air circulating through the workings. It was found 

 that a glass jar, of six inches in length and one inch in dia- 

 meter, filled with fire-damp, and left open with its mouth 

 downwards, continued to retain an explosive mixture for twenty 

 minutes. Now it is very desirable that the fire-damp should 

 be mingled as soon as possible with the whole circulating 

 stream of air, as beyond a certain degree of dilution it ceases 

 to be explosive. Mr. Buddie has stated, " that immediately 

 to the leeward of a blower, though for a considerable way the 

 current may be highly explosive, it often happens that after it 

 has travelled a greater distance in the air-course, it becomes 

 perfectly blended and mixed with the air, so that we can go 

 into it with candles; hence, before we had the use of the 

 Davy lamp, we intentionally made ' long runs,' for the pur- 

 pose of mixing the air." It is recommended that means be 

 taken to promote an early intermixture of the fire-damp and 

 air ; the smallest force is sufficient for this purpose ; as a down- 

 ward velocity of a few inches in the second will bring the light 

 gas from the roof to the floor. The circulating stream might 

 be agitated most easily by a light portable wheel, with vanes* 

 turned by a boy, and so placed as to impel the air in the di- 

 rection of the ventilation, and not to impede the draft. The 

 gas at the roof undoubtedly often acts as an explosive train, 



