. Dental metallurgy, for the use of dental students and practitioners. Fig. 20.—Adjustable laboratory blast lamp, fitted with adjustable standand tripod. (Central Scientific Company.) HEATING DEVICES 81 of. The blow-pipe in its simplest form is used by a blastfrom the mouth. The large end of the instrument is heldbetween the lips and the small end toward the flame. Theblast should not be sustained by the respiratory organs, but,in order that an unbroken current may be kept up, the mouthshould be filled with air, to be forced through the blow-pipe. by the muscles of the cheeks. While these are
. Dental metallurgy, for the use of dental students and practitioners. Fig. 20.—Adjustable laboratory blast lamp, fitted with adjustable standand tripod. (Central Scientific Company.) HEATING DEVICES 81 of. The blow-pipe in its simplest form is used by a blastfrom the mouth. The large end of the instrument is heldbetween the lips and the small end toward the flame. Theblast should not be sustained by the respiratory organs, but,in order that an unbroken current may be kept up, the mouthshould be filled with air, to be forced through the blow-pipe. by the muscles of the cheeks. While these are forcing theair through the blow-pipe, the connection between the chestand the cavity of the mouth should be closed by the palate,which thus performs the part of a yalve. The beginner isliable to fall into the error of not closing the connectionbetween the chest and the mouth at the proper instant, so asto obtain the force necessary to propel the air through theblow-pipe from the lungs. To avoid tiring the muscles of the Fig. 22 lips by continual blowing, the trumpet mouth-piece has beenrecommended (Figs. 21 and 22). This is merely pressedagainst the open mouth, and an uninterrupted blast maybe kept up for a long time without causing fatigue of theorbicularis oris, since that muscle takes but a passing partin the 82 METALLURGICAL APPARATUS The blow-pipe should be constructed of either brass orGerman silver, as these alloys are but poor conductors ofheat. A long-continued and steady flame maintained by themouth blow-pipe is apt t
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Keywords: ., bookcentury1900, bookdecade1910, bookpublisherphila, bookyear1917
