it should be made of platinum, so that it may be ignited. Two of these
platinum tubes should be supplied, differing in the size of the
orifice, by which a stronger or lighter current of flame may be
projected from it. Metals, such as brass or German silver, are very
liable to become dirty through oxidation, and when placed between the
lips are liable to impart a disagreeable taste. To avoid this, the top
of the tube must be supplied with a mouthpiece of ivory or horn C. The
blowpipe here represented is the one used by Ghan, and approved by
Berzelius. The trumpet mouthpiece was adopted by Plattner; it is
pressed upon the lips while blowing, which is less tiresome than
holding the mouthpiece between the lips, although many prefer the
latter mode.

[Illustration: Fig. 1]

Dr. Black's blowpipe is as good an instrument and cheaper. It
consists of two tubes, soldered at a right angle; the larger one, into
which the air is blown, is of sufficient capacity to serve as a
reservoir.

A chemist can, with a blowpipe and a piece of charcoal, determine many
substances without any reagents, thus enabling him, even when
travelling, to make useful investigations with means which are always
at his disposal. There are pocket blowpipes as portable as a pencil
case, such as Wollaston's and Mitscherlich's; these are objectionable
for continued use as their construction requires the use of a metallic
mouthpiece. Mr. Casamajor, of New York, has made one lately which has
an ivory mouthpiece, and which, when in use, is like Dr. Black's.

[Illustration: Fig. 2]