BLOWPIPE APPARATUS. 



(made up of inflammable gases) and the yellow one. To 

 obtain the reducing flame the blowpipe jet should be just 

 over the wick of the candle or lamp (Fig. 19). The speci- 

 men should be kept in the luminous part of the flame for 



FIG. 19. R KEDUCIXG POINT. 



some time. To obtain good results in this flame is not 

 always easy to a beginner, who, however, will be more suc- 

 cessful with the oxidizing flame. At or beyond the extre- 

 mity of the yellow one (the whole of the gases being con- 



FIG. 20. O OXIDIZIXG POIXT. 



sumed) bodies are combined with oxygen, and this is called 

 the "oxidizing " flame. To produce it properly, the blow- 

 pipe should be placed a little farther into the flame, and the 

 operator should blow more strongly (Fig. 20). 



FIG. 21. 



Treatment in a tube closed at one end (Fig. 21) is best 

 conducted over a spirit lamp. When the substance is to be 

 heated in an open glass tube (Fig. 22), the tube should be 

 inclined so as to allow a current of air to pass through 



