Alcoholic Fluids, Oils, S^c. in Lamps. 57 



ence to which it properly belongs ; the structure of a flame has 

 reference to what is cognizable by the naked eye. 



When combustibles that are compounds of hydrogen are 

 burned, so as to produce a blue flame, without the assistance of 

 a blowpipe, or any similar contrivance, the flame appears in its 

 most simple form, and two parts are to be distinguished. The 

 one appears immediately exterior to the cone of gas or vapour, 

 and, as seen on each side of the flame, has the appearance of a 

 bright blue line, extending from the base to the apex of the 

 cone. It must be unnecessary to explain how this part of the 

 flame is only to be distinguished at the sides, though it sur- 

 rounds the whole of the cone. Exterior to this narrow blue line, 

 is an attenuated portion of an opaline or misty blue colour, 

 which extends about the tenth of an inch, more or less, beyond 

 the blue line, and whose exterior surface is ill defined, resem- 

 bling a brush. This exterior portion surrounds the whole flame ; 

 and though its presence might not, in every instance, be suspect- 

 ed at certain parts of the flame, it surrounds the whole of white 

 flames, when these are properly adjusted. 



When the substances formerly mentioned are burned, so as 

 to extricate white light, the white portion appears interior to 

 the narrow blue line, but the former never extends to the base 

 of the flame, and the latter can only be traced to a short dis- 

 tance on the exterior of the white portion. 



On examining the flame of a properly adjusted candle, the 

 blue line exterior to the white light is observed to disappear op- 

 posite to the apex of the transparent cone surrounding the wick, 

 or at that part where the white light is extricated with great 

 effulgence *. The same thing takes place with the exterior at- 

 tenuated opaline brush, v/hich is not readily distinguished above 

 the middle height of the flame, where the white light becomes in- 

 tense. In this instance, the attenuated blue flame seems to be ren- 

 dered invisible by the intensity of the white light. If, even in foggy 

 weather, with an overcast sky, a blue and white flame of diluted 



* In a blue and white spirit-flame, the bright blue lines are seen extending ori 

 the exterior of the white portion ; and between their upper extremities is a broad 

 arch or belt of a dark blue colour, which surrounds the upper part of the white 

 portion, and is observed occasionally to conceal or darken its apex. See Fig.' 7. 

 in which this flame is represented in outline. 'i' s 



