320 On the Common Blowpipe. 
Even a picce of the stem of a tobacco pipe can be used as a 
blowpipe when no better means are at hand. 
In experiments requiring a long continued blast, the moisture of 
the breath condenses in the tube in such quantities as to be inconve- 
vient, and the best blowpipes are provided with a small chamber to 
collect this moisture, and prevent its being forced out at the orifice 
into the flame. : 
Fig. 2. 
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Fig. 2, shows the parts of a blowpipe provided with a chamber 
C. At D is aconical orifice which slips into the projection from the 
chamber. At E is a small perforated cone, to be placed over the 
end of D when a smaller orifice is required. 
Fig. 3. 
Fig. 3 shows the blowpipe arranged for use. 
In using the blowpipe it is highly important to be able to keep up 
a well regulated and long continued blast. The power to do this 
can be acquired only by practice, but the following directions, taken 
from Shepard’s Mineralogy, will facilitate the acquisition. * Closing 
the mouth, keep the cheeks distended with air, during a number of 
inspirations and expirations performed through the nostrils. Next 
attempt the same with the mouth-piece of the blowpipe between 
the lips: now as this provides an exit for the air in the mouth, the 
cheeks will soon collapse ; to prevent this at the moment of expira- 
tion through the nose, a sufficient quantity of air must be allowed to 
enter the mouth to preserve their distention. By this means the air 
in the mouth is constantly subject to the same compression and flows 
in a uniform manner from the little orifice. Having acquired the 
habit of keeping up a continued current of air from the blowpipe; 
the beak is now brought within the border of the flame of a lamp or 
