56 Mr H. H. Blackadder on the Combustion of 



and the consumption is so regular and uniform, that, when a 

 lamp is constructed in the form of a floating syphon, it is found 

 to measure time with great accuracy. 



Tallow, and other solid combustibles, of a similar nature, may 

 also be burned without a wick. In such cases, it is only neces- 

 sary to melt a small quantity of the solid substance^ with the 

 end of a hot wire or rod of glass ; or to introduce a little oil into 

 a hollow, previous to introducing the floating burner. After- 

 wards, the heat of the flame is suflicient to keep up a supply of 

 fluid. 



It is well known, that volatile oils, such as turpentine, give 

 out so much carbon in the form of soot, during their combus- 

 tion, as to prevent their being hitherto burned in a lamp, for the 

 purpose of illumination. Turpentine, however, may be burned 

 in a lamp, so as not only to give out no carbon in the form of 

 soot, butto afibrd a beautiful white light, which, in splendour, 

 far exceeds that given out by the fixed oils : — this was exhibit- 

 ed on a small scale, by means of a small experimental glass lamp. 

 All the fixed oils are rendered empyreumatic, previous to 

 combustion ; and the same change is necessary in the case of 

 turpentine, but, from its volatile nature, is less readily produced. 

 From the extreme whiteness and splendour of the flame of 

 turpentine, there is reason to expect, that it may yet be ap- 

 plied to valuable purposes. The preceding details have been 

 entered into, with the view of facilitating investigation, and 

 were, to a certain extent, necessary to the next part of the sub- 

 ject. 



2. — Of the Colour of Flame. 

 Previous to entering on the subject of the colour of flame, it 

 is necessary to attend to what, for the sake of distinction, may 

 be termed its structure. Exterior to the central cone of gas or 

 vapour, that is, in the proper flame, there are parts which can 

 readily be distinguished, and which distinctly differ from each 

 other. One part may be changed, or a part may be made to 

 disappear, while the others remain unaffected. By means of a 

 prism, the light of any flame may be shewn to be composed of 

 several colours : — that, however, is a separate investigation, and 

 which is left to those who are conversant in the branch of sci^^ 



