L1THOLOGY. 99 



in a more or less inclined direction. The stream of air 

 must be constant and regular, also properly directed 

 and applied. It is in the power of the operator to 

 direct either an oxydising or a reducing flame upon 

 the body he subjects to its action. 



" In order to obtain a reducing flame (for depriving a 

 substance of its oxygen) the nozzle of the blow-pipe is 

 held in an inclined direction parallel to the surface of 

 the wick and just touching the exterior surface of the 

 flame, a bright yellow flame will be thus produced. An 

 oxydising flame (for bringing about the oxydation of a 

 substance) is obtained by keeping the nozzle at the 

 same inclination, introducing it into the flame to about 

 one-third the breadth of the wick, and blowing a some- 

 what stronger blast the flame so produced is of a pale 

 blue colour and almost invisible by daylight. 



" If a small fragment of an oxydisable substance be 

 held just beyond the point of the oxydising flame it 

 becomes intensely heated, and, being exposed freely to 

 the action of the surrounding atmosphere, it is rapidly 

 oxydised. This flame, on account of its great heating 

 power, is also employed in order to ascertain the fusi- 

 bility of various substances, and for effecting fusions in 

 all cases in which a reducing action is not essential. 



" When any substance is submitted to the action of 

 the reducing flame it should be so held as to be entirely 

 surrounded by the yellow flame, and protected from the 

 oxydising action of the air; but this condition being 

 fulfilled, it should be held as near as possible to the 

 point of the flame in order to gain the greatest amount 

 of heat."* 



* " Scheerer and Blandford on the Blow-pipe." 1864. 



72 



