When it is desired to charge the apparatus, a leaden cylinder, 1.34 inches long and 1.3 inches in diameter, is placed in one of the heads, and the median piece is so screwed that it can be made still tighter by a few turns.  Then a 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.

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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, and the upper part of which is protected against the action of the acid vapors disengaged during distillation by a lining of refractory clay.  The stone cover, B, is provided with an aperture, b, through which the