Mr Blackadder on the Constitution of Flame. 229 



so attenuated, that, on looking at an object, such as a slip of 

 paper, through the middle of the lower half of the flame, it is 

 seen as through glass, or other transparent media. Hence, 

 when the flame is viewed at a distance, an oval space is obser- 

 ved around the wick, which has a dusky or non-luminous ap- 

 pearance ; but, when more closely examined, luminous particles 

 of a yellowish white colour are observed on its interior surface, 

 and which appear to move rapidly in parallel lines, and from 

 below upwards. This oval space serves to point out the exact 

 height to which the blue portionof the flame extends, and the part 

 of the flame which alone contains the white vapour formerly de- 

 scribed. 



Stilly y An interior cone of white light, the base of which is 

 above the upper part of the blue portion. This is the whitest, 

 most luminous, and last evolved part of the flame. When the 

 combustion is moderate, and the wick properly adjusted, the 

 apex of diis cone remains within that of the exterior cone ; but 

 it almost constantly exhibits a disposition to protrude, and then 

 produces the appearance of a notch or break on each side of the 

 apex of the flame. Beyond a certain extent, however, it can- 

 not thus protrude, without interrupting the process of combus- 

 tion at the upper part of the flame. More or less charcoal is 

 then discharged, in the form of soot, and which, in becoming 

 partially ignited, gives out light of a brown or reddish yellow co- 

 lour ; and it may be remarked, that it is the exterior cone that 

 first and principally exhibits the effects of this interruption. 



In the interior of the upper half of the flame, or in that 

 which, for the sake of distinction might be termed its upper 

 chamber, there is present a vapour of peculiar properties, and 

 which is altogether different from that which is found in the 

 lower chamber, or within the blue portion. When the vapour 

 referred to is collected, it has a misty appearance from the pre- 

 sence of minute particles of charcoal, and even remains slightly 

 obscured, after having been repeatedly agitated with water. No 

 oil or water is deposited from it, and though it has a suffocating 

 odour, it is altogether free of the offensive smell proper to the 

 •dense vapour formerly described. It would be desirable to as- 

 certain the exact chemical nature of this vapour, but such an 

 analysis is not unattended with difficulty, and other pursuits of 

 n professional nature, present too many obstacles tp such an jn^ 



