desired to light a burner, pressing the button causes the flame to shoot
near enough to each burner to ignite the gas. However, whether the
burners are lighted in this way or by applying a lighted match, they
should never be lighted until heat is required; likewise, in order to
save gas, they should be turned off as soon as the cooking is completed.

[Illustration: Fig. 6]

To produce the best results, the flame given off by gas should be blue.
A flame that is yellow and a burner that makes a noise when lighted,
indicate that the gas flame has caught in the pipe, and to remedy this
the gas must be turned out and relighted. When the gas flame coming from
a new burner is yellow, it may be taken for granted that not enough air
is being admitted to make the proper mixture. To permit of the proper
mixture, each gas pipe extending from the stop-cock and terminating in
the burner is provided with what is called a _mixer_. This device, as
shown in Fig. 6, consists of several slots that may be opened or closed
by turning part _a_, thus making it a simple matter to admit the right
amount of air to produce the desired blue flame. If burners that have
been in use for some time give off a yellow flame, it is probable that
the trouble is caused by a deposit of soot or burned material. Such
burners should be removed, boiled in a solution of washing soda or lye
until the holes in the top are thoroughly cleaned, and then replaced and
adjusted. As long as the flame remains yellow, the gas is not giving off
as much heat as it should produce and is liable to smoke cooking
utensils black. Therefore, to get the best results the burners should be
thoroughly cleaned every now and then in the manner mentioned. Likewise,
the pan beneath the burners, which may be removed, should be cleaned
very frequently, and the entire stove should be wiped each time it is
used, for the better such a stove is taken care of, the better will it