GFZ) 
Il.—On the Constitution of Flame. By Wittiam Swan, Esq. 
(Read 17th January 1859.) 
If we examine the flame arising from the combustion of any of the hydro- 
carbons, such as that of coal-gas, or of a common candle, it will be found to con- 
sist of several portions easily distinguishable by the eye, and in which the matter 
composing the flame exists in very different conditions. There is, fist, a central 
non-luminous region, in which the gases are not yet ignited; secondly, a blue 
conoidal envelope, extending from the wick or burner, and gradually thinning out 
towards the top of the flame; ¢hzrd/y, a more or less luminous conoid, thin to- 
wards the bottom of the flame, where it is enveloped by the blue conoid, but 
thicker towards the top. And fowrthly, a faintly luminous outer envelope, com- 
pletely surrounding the other portions of the flame, and greatly developed towards 
the top. 
In the blue part of the flame, where the supply of oxygen is abundant, the 
carbon seems to undergo combustion in a gaseous state along with the hydrogen. 
In the interior luminous region, where there is less free oxygen, carbon is disen- 
gaged in a solid form, and the brilliant light which is generated arises from the 
incandescence of its particles. The exterior envelope is supposed to consist of 
matter which has undergone combustion, but which is still at so high a tempera- 
ture, as to be incandescent. 
When a flame is urged by a blow-pipe, a large supply of oxygen is forced 
into it. The greater portion of the carbon, which otherwise would have ap- 
peared in a solid form, before undergoing combustion, is consumed in a gase- 
ous state. The blue part of the flame thus becomes greatly developed, and 
appears as a sharp well defined cone; while the faintly luminous envelope sur- 
rounding it also assumes a regular conical form. The inner blue and outer 
faintly luminous cones are well known to chemists as possessing very diverse 
properties. In the outer cone, from the presence of an excess’ of oxygen, bodies 
become rapidly oxidated ; while in the inner cone, from the redundance of uncom- 
bined inflammable matter, a powerful deoxidizing energy is exerted. Such are 
the principal facts hitherto recognised regarding the constitution of flame. 
Two years ago, when I was engaged in a series of experiments on the pris- 
matic spectra of the flames of the hydro-carbons, my attention became directed to 
Professor DRAPER’s very ingenious paper, “On the Production of Light by 
Chemical Action,” in the 32d vol. of the London Philosophical Magazine. In 
that paper, the author advances an entirely new view regarding the nature of 
VOL. XXII. PART 1. F 
