by Chemical Action. Ill 



outside of the flame, corresponding to the two great groups of 

 fixed lines. Perhaps through all these inactive parts the in- 

 combustible nitrogen chiefly escapes. 



VI. Effects of the introduction of air into the interior of a 

 jictme, jwoducing the destruction of the red and orange strata^ 

 and converting them into violet. 



It now becomes a curious subject of inquiry to determine 

 what must take place when an ordinary flame is disturbed 

 by the introduction of air into its interior. When a blow- 

 pipe jet is thrown through the flame of an oil-lamp, the sharp 

 blue cone which forms, indicates, on the principles here set 

 forth, that the combustion is much more active. But if the 

 colours of a common flame come from different depths, the 

 red being the innermost, it is clear that the introduction of a 

 jet of air by a blowpipe should make the combustion rapid 

 where before it was slowest, and the less refrangible colours 

 ought to be destroyed. A prismatic analysis should exhibit 

 the spectrum of a blowpipe flame without any red or orange. 



In this examination no slit is requned, as in the former ex- 

 pei"iments, for the cone itself when at a distance of six or eight 

 feet is narrow enough for the purpose : it yields a very ex- 

 traordinary spectrum. As was anticipated, I found that all 

 the red rays were gone, and not a vestige of either them or 

 the orange could be seen. But the spectrum was divided into 

 five well-marked regions, separated from one another by in- 

 active spaces; in short, I saw five distinct images of the blue 

 cone, one yellow, two greens, one blue, and one violet. In fig. 1, 

 No. 10, this result is represented. 



This experiment may be verified without a telescope. On 

 looking through a prism set horizontally at its angle of mini- 

 mum deviation, at the blowpipe cone some six or eight feet 

 distant, there will be seen a spectrum of that part of the flame 

 which does not join in the production of the blue cone. It 

 contains of course all the prismatic colours. But projecting 

 from this are five coloured images of the cone; one yellow, two 

 greens, one blue, and one violet. They are entirely distinct 

 from one another, and are parted by dark spaces, fig. 2. (p. 107.) 



Such is the efiect of introducing air into the interior of a 

 flame and destroying those strata that yield the red and orange 

 colours. The effect of a blowpipe is to produce a double stra- 

 tum of blue light, one being external, the other internal ; also 

 two strata of green, one again external, the other internal; 

 and the escaping products of combustion, steam and carbonic 

 acid, mingled with atmospheric air, constitute the oxidizing 

 flame which envelopes the blue cone and emits Brewster's 



