E, E are two pieces of ordinary combustion tubing, having a length of
about 650 or 700 mm., in which is placed the permanganate solution
employed for the absorption of the nitric oxide. Their open ends are
provided with lips in order to facilitate the pouring of liquids from
them, care being taken not to so distort the ends that rubber stoppers
cannot be made to fit them tightly. They are placed in a nearly
horizontal position in order to diminish the pressure required to
force the gases through the apparatus and thus lessen the danger of
leakage through the rubber joints.
_a_ is a tube through which the ferrous chloride and hydrochloric acid
are introduced into B, as in the method of Tiemann-Schulze.
_b_ serves for the introduction of carbon dioxide to expel the air
before the decomposition of the nitrate, and the nitric oxide
afterward.
_c_ is an unbroken tube ending at the lower surface of the stopper in
B, and at the bottom of C.
The rubber joint, _d_, is furnished with a Mohr and also a screw pinch
cock. The joints, _e_ and _f_, are furnished with Mohr pinch cocks.
The rubber tubing upon these should be of the best quality, and must
be carefully tied.
[Illustration: DETERMINATION OF NITRIC ACID.]
THE SOLUTIONS.
In consequence of the large volume of the permanganate solution
required for the complete absorption of the nitric oxide, we have
found it advantageous to use three solutions instead of two.
Pages:
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171