14 
BULLETIN 102, UNITED STATES NATIONAL MUSEUM. 
ondary air, will be taken from the atmosphere surrounding the burn- 
ing flame. Such a blue flame does not smoke or deposit free carbon 
on a cool surface, although if the flame is sufficiently chilled some of 
the gas will escape unburned. 
The action of the mixer is shown in Figure 8. The gas, at pres- 
sures above atmospheric air, is forced through a small hole by the 
pressure in the gas pipe, and thus acquires a relatively high velocity 
in passing through the small spud opening. In this way an aspirat- 
ing or sucking action is produced around the orifice and this draws in 
S SECONDARY AIR GOES TO FLAME FROM SUFPOUNO/NG ATMOSPHEFE 
atmospheric air from the room so it will mingle with the gas. A gas 
mixer is, therefore, in effect merely a small air injector. The amount 
of air going in may be varied by adjusting the air shutter. 
The mixer shown is of the type always used on cooking stoves, all 
hot-water heaters, all incandescent mantle lamps, room heaters of the 
radiant type, many other room heaters, and all house-heating fur- 
naces or boilers. 
LUMINOUS-FLAME BURNERS. 
If manufactured gas is forced out through a small hole, about the 
diameter of a pin, enough air can be mixed with the issuing gas to 
insure perfect combustion. This is the 
principle of the yellow or luminous flame 
burner, as shown in Figure 9. The flames 
must not be permitted to come in contact 
with any solid body, because if they do 
they will deposit carbon and probably 
produce carbon monoxide. Only very 
small quantities of manufactured gas can 
be burned in such burners. In this yel- 
low or luminous type of flame the production of the light is due to 
the incandescence of momentarily existing carbon particles furnished 
by the decomposition, by heat, of the gas itself, before coming in 
contact with the air. 
- YELLOW L UM/NOUS FLAME MUST 
NOT TOUCH ANY PART OF STOVE 
AND SHOULD NOT BLOW AT T/F> 
-T/P W/TH P/N HOLE 
GAS P/PE ' 
FIG. 0. — ACTION OF LUMINOUS- 
FLAME BURNER. 
