steel plate, k, 1.3 inches wide by 0.2 inch thick,
is placed against the cylinder, and against this plate again is placed a
cardboard disk, 1.34 inches wide by 0.4 inch thick. This completely
closes the hollow space. The steel plates and heads are marked with the
figures 1 and 2, which, through the pressure, are impressed upon the
leaden cylinders. Then the charge of powder, weighing exactly 300
grains, is introduced, and a new cardboard disk, a steel plate, and a
leaden cylinder are inserted, and the second head is screwed up. The
apparatus is now ready to operate. An ordinary priming is placed on the
pyramid, h, and the plug with the valve is screwed down in such a way
that the latter shall have a little play. By means of a hammer, m, a
smart blow is given the valve i, and this detonates the priming, and
causes an explosion of the charge. The gases make their exit through the
pyramid, h, and lift the valve and press it against the plug, so that
their escape is effectually prevented. In fact, the explosion takes
place without noise. A slight whistling, only, indicates that the
capsule has not missed fire, and that the apparatus may be immediately
opened, the gases having condensed in the interior. It is well, however,
to place the closed apparatus in water, in order that the residua that
have entered the threads of the screw may become detached, and that the
apparatus may be opened easily. Although there is no danger in standing
alongside the apparatus, it is much better to spring the hammer by means
of a cord of a certain length, since the valve and especially the
pyramid gradually burn and may be thrown out. With some kinds of powder
the pyramid rapidly melts, and must be frequently replaced.

[Illustration: APPARATUS FOR MEASURING THE FORCE OF EXPLOSIVES.]

The two cones of lead obtained are then measured to 0.004 of an inch by
means of a gauge (Fig. 3).

The inventor has made numerous experiments with his apparatus, and
thinks it permits of determining the total force developed by powder
very perfectly.

* * * * *

SANDMANN'S VINEGAR APPARATUS.

For obtaining anhydrous or very concentrated vinegar directly from
pyrolignite of lime or other acetates by a single distillation, Mr. D.
Sandmann, of Charlottenburg, employs the apparatus shown in the
accompanying engraving. It consists of a double-bottomed copper or
enameled iron boiler, A, arranged for being heated by steam,