252 Mr Blackadder on the Constitution ()f Flame. 



tinguish a candle, and from this it might be inferred, that more 

 heat is consumed in converting tallow into a fluid than is carried 

 off by the wick-holder of a common lamp ; but, in a common 

 lamp, much of the heat that is abstracted by the metallic wick 

 holder, is communicated to the oil in the reservoir. A lamp 

 without a wick may readily be extinguished by abstracting heat 

 from the burner. 



If a small stream of water, projected from a tube, be direct- 

 ed through the flame of a candle, the stream being made to pass 

 immediately above the wick, the form of the flame is thereby 

 scarcely aff^ected ; white light is defective at the spot where the 

 water enters and comes out of the flame, and in this much only 

 is the combustion interrupted. On receiving the water into a 

 vessel, after it has passed through the flame, a film of tallow is 

 observed to form on its surface, and which is derived from the 

 vapour in the interior of the flame ; part of which has been car- 

 ried off* and condensed by the water. When the stream is di- 

 rected through the white part of the flame that is above the oval 

 space formerly mentioned, the effect produced on the flame is si- 

 milar ; no tallow, however, is observed on the surface of the wa- 

 ter ; but, instead thereof, a considerable quantity of carbon, in 

 the form of soot, is deposited. When the water is made to pass 

 through the flame, near its apex, the combustion is interrupted, 

 and the top of the flame acquires a brown colour. The same 

 effect is produced by a solid body, and likewise by a stream of 

 air ; and hence it might appear, that the interruption of the com- 

 bustion was simply a consequence of the abstraction of heat ; 

 but the flame of a spirit-lamp, when propelled on the apex of the 

 flame of a candle, interrupts the combustion, and gives the lat- 

 ter a brown colour. The following facts, illustrative of the ex- 

 trication of white light, may also be noted. When any solid 

 body ifi approached to the flame of a candle, so as to be at the 

 distance of about three-tenths of an inch from its surface, the 

 part of the flame that is immediately above, exhibits a sensi- 

 ble increase of white light ; but when the solid body is brought 

 to within the tenth of an inch of the opaline brush, the space 

 which formerly presented an increase of white light is now alto- 

 gether deprived of itj the flame remaining in other respects un- 

 changed. The space that is deprived of white light has a rela- 

 j^ion to the form and size, but to no otlior property of the solid 



