Notices respecting Nexo Booh. 385 



cument, displaying his earliest views, and tending to illustrate the 

 history of their progress." 



" The fire-damp I find, by chemical analysis, to be (as it has 

 been always supposed) a hydro-carbonate. It is a chemical com- 

 bination of hydrogen gas and carbon, in the proportion of 4 by 

 weight of hydrogen gas, and 11^ of charcoal. 



" I find it will not explode, if mixed with less than six times, or 

 more than fourteen times its volume of atmospheric air. Air, 

 when rendered impure by the combustion of a candle, but in which 

 the candle will still burn, will not explode the gas from the mines ; 

 and when a lamp or candle is made to burn in a close vessel having 

 apertures only above and below, an explosive mixture of gas ad- 

 mitted merely enlarges the light, and then gradually extinguishes it 

 without explosion. Again, — the gas mixed in any proportion with 

 common air, I have discovered, will not explode in a small tube, the 

 diameter of which is less than J.th of an inch, or even a larger tube, 

 if there is a mechanical force urging the gas through this tube. 



" Explosive mixtures of this gas with air require much stronger 

 heat for their explosion than mixtures of common inflammable 

 gas*. Red-hot charcoal, made so as not to flame, if blown up by 

 a mixture of the mine gas and common air, does not explode it, 

 but gives light in it; and iron, to cause the explosion of mixtures 

 of this gas with air, must be made xvhite-hot.. 



" The discovery of these curious and unexpected properties of 

 the gas leads to several practical methods of lighting the mines 

 without any danger of explosion. 



" The first and simplest is what I shall call the Safe lamp, in 

 which a candle or a lamp burns in a safe lantern, which is air-tight 

 in the sides, which has tubes below for admitting air, a chamber 

 above, and a chimney for the foul air to pass through ; and this is 

 as portable as a common lantern, and not much more expensive. 

 In this, the light never burns in its full quantity of air, and there- 

 fore is more feeble than that of tlie common candle. 



" The second is the Btoiving lamp. In this, the candle or lamp 

 burns in a close lantern, having a tube below of small diameter for 

 admitting air, which is thrown in by a small pair of bellows, and a 

 tube above of the same diameter, furnished with the cup filled with 

 oil. This burns brighter than the simple safe lamp, and is extin- 

 guished by explosive mixtures of the fire-damp. In this apparatus 

 the candle may be made to burn as bright as in the air ; and sup- 

 posing an explo.sion to be made in it, it cannot reach to the ex- 

 ternal air. 



" The third is the Piston lamp, in which the candle is made 

 to burn in a small glass lantern furnished with a piston, so con- 



* ■' Olrfianl gas, wlien mixed with such f)roportions of common air as to 

 render it e.x|ilosivc, is fired isotli liy ch;irco:il aiul iron heated to a dull-red 

 heat. Geisroiis oxide of carlxin, wliicii explodes when mixed with two parts 

 of air, is likewise inHamiiiahle by rcci-iiot iron and charcoal. The case is 

 the same with sit/p/turctled hi/ilrogen." 



N. S. Vol. 10. No. 59. Nov. 1831. 3D structcd 



