98 OXYGEN EXTINGUISHES COMBUSTION. 



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gases, lie'foimd reason to conclude, that when explosions occur 

 from sparks of the steel-mill for lighting mines, the mixture of 

 fire-damp, or carburetted hydrogen, with the atmospheric air, 

 is in the proportion required to consume all the oxygen of the 

 air; and that it is only in about this proportion, that explosive 

 mixtures can be fired by electrical sparks from a common 

 machine. 



When a taper is burning in a mixture of carburetted hydro- 

 gen and atmospheric air, in the proportion of 1 to 12, the 

 flame of the wick is seen within that of the fire-damp ; when 

 the mixture is in the ratio of 1 to 7 of the air, the flame of the 

 wick is no longer visible ; in the latter case, the color of the 

 flame is, at the lower part, green ; middle, purple ; upper part, 

 Hue ; showing, that in the lower part the nitrogen and hydro- 

 gen appeared green ; in the middle the carbon, purple ; and at 

 the top hydrogen, blue, prevailed ; but, evidently, oxygen was 

 insufficient in proportion to produce perfect white light. 



Now we also find that if oxygen, which is an admitted 

 evident supporter of combustion, is added, in greater proportion 

 than 2J times the volume, to 1 of carburetted hydrogen, the 

 LATTER CEASES TO BURN. We also find that carburetted hy- 

 drogen burns when mixed with atmospheric air, as 1 to 7 

 (when it is most explosive), at 1 to 15 of air, and even at 1 to 

 30 ; and that a mixture of 1 of nitrogen, gas to 6 of explosive 

 fire-damp, or 1 of carbonic-acid gas to 7 of fire-damp, can 

 totally paralyse their explosive powers. This must be occa- 

 sioned by the particular law of combination, dependent on pola- 

 rity and electrical affinity ; as carbonic-acid gas is a compound 

 of carbon, a combustible, and oxygen, a supporter, as they are 

 termed. It would appear that the order of combination, dis- 

 played in the formation of carbonic-acid gas, by the union of 

 oxygen and carbon, is such, that the second atom of oxygen 

 interposes as a protection against inflammation,, by exhibiting 

 contrary poles on the surface of the compound spherical atom, 

 to those essential for the production of radiant matter, or light ; 



