GENERAL OPERATIONS

33

In the Teclu burner (Fig. 13) the gas is controlled by the
screw on the side of the base while the disc at the bottom of the
cone controls the air supply.
In this burner the regulation of gas flow is not accomplished
by altering the pressure under which it is delivered but by chang-
ing the size of the orifice in the burner. The maximum pressure
is thus used at all times and the result is a better mixture of gas
with air than is obtainable by
regulating the gas cock of the
supply line.
A very common error on the part
of students lies in carelessness with
regard to the regulation of flames.
If a relatively cool flame is re-
quired and if a deposit of carbon
is not objectionable the air should
be excluded from the mixer. If,
on the other hand, the highest
efficiency of the burner is desired,
careful regulation of the air and
gas is necessary. The inner blue
cone should be well defined and it
should not show a yellow tip. If
more air is admitted than that
required to burn the gas com-
pletely with production of a "blue ^
flame, the result is a roaring and f_ig. 13.—Section of Toolu burner,
fluttering flame. This means that
more air is being admitted than can be used and this air, in being
heated by the flame, lowers the temperature of the latter.
Meker Burner.—A somewhat radical departure from the older
types is found in the M£ker burner. This is shown in section
in Fig. 14. The air is drawn in through several holes in the base
of the tube. The delivery of the gas under pressure into the
inverted cone which forms the burner tube causes a greater
reduction of pressure within the tube than is the case with
burners having cylindrical tubes. The result is a greater inflow
of air, making possible the combustion of a greater amount of gas
in a given space, and also more complete mixing of gas and air.