greatly increased.

_The Blast of Air._--By using the blowpipe for chemical purposes, the
effect intended to be produced is an uninterrupted steady stream of
air for many minutes together, if necessary, without an instant's
cessation. Therefore, the blowing can only be effected with the
muscles of the cheeks, and not by the exertion of the lungs. It is
only by this means that a steady constant stream of air can be kept
up, while the lungs will not be injured by the deprival of air. The
details of the proper manner of using the blowpipe are really more
difficult to describe than to acquire by practice; therefore the pupil
is requested to apply himself at once to its practice, by which he
will soon learn to produce a steady current of air, and to distinguish
the different flames from each other. We would simply say that the
tongue must be applied to the roof of the mouth, so as to interrupt
the communication between the passage of the nostrils and the mouth.
The operator now fills his mouth with air, which is to be passed
through the pipe by compressing the muscles of the cheeks, while he
breathes through the nostrils, and uses the palate as a valve. When
the mouth becomes nearly empty, it is replenished by the lungs in an
instant, while the tongue is momentarily withdrawn from the roof of
the mouth. The stream of air can be continued for a long time, without
the least fatigue or injury to the lungs. The easiest way for the
student to accustom himself to the use of the blowpipe, is first to
learn to fill the mouth with air, and while the lips are kept firmly
closed to breathe freely through the nostrils. Having effected this
much, he may introduce the mouthpiece of the blowpipe between his
lips. By inflating the cheeks, and breathing through the nostrils, he
will soon learn to use the instrument without the least fatigue. The
air is forced through the tube against the flame by the action of the