Page:McClure's Magazine v9 n3 to v10 no2.djvu/109

Rh height; that it could sustain any degree of shock without explosion. He claimed for blasting gelatin that, in addition to being the strongest, it was absolutely the safest explosive known. In proof of this he devised a series of experiments which have been often performed at the factory and which have never failed. They may be seen at any time by a visitor whom the company desires to convince, and as given on a late occasion were as follows:

1. A cube of iron weighing 420 pounds was hoisted on crossed poles above an ordinary packing-box containing fifty pounds of dynamite cartridges, the box resting on a board on the ground. The rope was cut by electrically exploding a cartridge against it, and the weight fell twenty-five feet, smashing the box completely and pulverizing some of the cartridges; but there was no explosion.

2. The same experiment was repeated with a box of blasting gelatin cartridges, the fall being twenty-five feet and the iron weight 470 pounds. Box and contents were crushed and scattered, but there was no explosion.

3. A one-pound tin of gunpowder was placed on an open five-pound box of dynamite cartridges and exploded. The dynamite caught fire and burned up, but did not explode.

4. The same experiment was performed with a five-pound box of blasting gelatin cartridges with the same result.

5. A dynamite cartridge was set on fire by a fuse, and burned rather rapidly. It would have burned away completely, but a detonator had been placed in the middle, and when the flame reached this the other half of the cartridge exploded.

6. To show the strictly local force of dynamite, a one-pound cartridge was hung eight inches above a three-eighths of an inch boiler-plate, which was lying on two bits of wood, and exploded. The plate was only slightly bent.

7. A similar cartridge was laid flat upon the same plate and exploded, the result being a hole torn in the plate about the size of the cartridge.

8. A similar cartridge was then placed on a similar plate and covered with sand. Upon exploding, it tore a large hole in the plate.

Dynamite and blasting gelatin when set on fire will merely burn. If the dynamite is in a loose form, it will entirely burn away without danger. If compressed, both will burn until the heat reaches a point high enough to explode the remainder, but this always requires sufficient time to give bystanders full warning and enable them to reach a point of safety. All the nitroglycerin compounds are exploded by detonation; that is, by means of explosive caps like percussion caps which fit on the ends of the fuses. The cap explosive is a mixture of fulminate of mercury and chlorate of potash, and the Nobel company have a large and separate factory in Scotland which is devoted to the manufacture of