GAS AS A FUEL 



155 



FIG. 120. 



SELF 



The burner consists of three parts: 



1. The barrel, a metal tube through which the gas passes. At 

 the foot of the barrel there are two or more 



holes to allow air to enter. 



2. A ring or device to open or close the 

 holes. 



3. A base, containing a small central gas 

 way called a " spud." 



Gas enters at the base, passes through the 



spud and through the barrel, forming a partial 



vacuum. Air enters the holes near the base, 



and mixes with this gas. When the holes are 



partly open, air enough enters to produce a 



non-luminous flame. When less air enters the holes near the base, 



the flame will be luminous. The luminous part of the flame is due to 



carbon particles which are heated very hot 

 by the burning gas. The temperature of the 

 yellow flame is very high, causing the gas 

 to break up and set free small particles of 

 carbon. When air is allowed to enter at 

 the bottom of the burner a non-luminous 

 flame is produced, since that part of the 

 gas from which carbon particles are set free 

 never gets hot enough to liberate them. 

 As the carbon particles in the luminous 

 flame move toward the outside of the flame 

 they come in contact with the oxygen of 

 the air and burn up. If still less air is sup- 

 plied, the carbon particles do not burn 

 even on reaching the outer part of the 

 flame, but appear as black smoke. A 

 piece of cold glass or earthenware placed 

 in the flame will cool some of the car- 

 bon particles and cause them to collect 

 as black soot. 



If too much air is admitted, the 



burner will be very noisy, If the flame is to be used for 



V./f.Or>AUNC GLOBC 



FIG. 121. 



