452 On the Fire-damp of Coal Mines, and on Methods 



large, it is scarcely possible that any explosion produced by the 

 flame can reach it. 



I threw into the safe- lantern with the common chimnev, a 

 mixture of 15 parts of air and 1 of fire-damp: the flame was 

 immediately greatly eidarged, and the flame of the wick seemed 

 to be lost in the larger flame of the fire-damp. I placed a 

 lighted taper above the orifice of the chimney: it was imme- 

 diately extinguished, but without the slightest previous increase 

 of its flame, and even the wick instantly lost its fire by being 

 plunged into the chimney. 



I introduced a lighted taper into a close vessel containing 15 

 parts of air and 1 of gas from the distillation of coal, suflTered it 

 to burn out in the vessel, and then analysed the gas. After the 

 carbonic acid was separated, it appeared by the test of nitrous 

 gas to contain nearlv 4- of its original quantity of oxygen ; but 

 detonation with a mixture of equal parts of hydrogen and oxy- 

 gen proved that it contained no sensible quantity of carburetted 

 hydrogen gas. 



It is evident, then, that when in the safe-lantern the air gra- 

 dually becomes contaminated with fire-damp, this fire-damp will 

 be consumed in the body of the lantern ; and that the air passing 

 through the chimney cannot contain any inflammable mixture, 



I made a direct ex])eriment on this point. I gradually threw 

 an explosive mixture of fire-damp and air into the safe-lantern 

 from a bladder furnislied with a tube which opened by a large 

 aperture above the flame ; the flame became enlarged, and bv a 

 rapid jet of gas I produced an explosion in the body of the lan- 

 tern ; there was not even a current of air through the safety 

 tubes at the moment, and the flame did not appear to reach 

 above the lower aperture of the chimney; and the explosion 

 merely threw out from it a gust of foul air. 



The second safety-lantern that 1 have had made is upon the 

 same principle as the first, except that instead of tubes, safety 

 canals are used, which consist of close concentric hollow me- 

 tallic cylinders of different diameters, and placed together so as 

 to form circular canals of the diameter of from -^~ to -^\ of an 

 inch, and an inch and -^-^ long, by which air is admitted in 

 much larger quantities than by the small tubes. In this arrange- 

 ment there is so free a circulation of air, that the chimney like- 

 wise may be furnished with safety canals. 



I have had lamjis made for this kind of lantern which stand 

 on the outside, and which may be supplied with oil and cotton 

 without any necessity of opening the lantern ; and in this case 

 the chimney is soldered to the top, and the lamp is screwed into 

 the bottom, and the wick rises above the air canals. 



I have likewise had glass lamps with a single wick," arjd Ar- 



gaud 



