MECHANICS AND USEFUL ARTS. 119 



Dynamite, which resembles coarse, dark-brown sand, is a solid 

 granular explosive, for which is claimed force of a remarkable 

 degree, and a harmlessness, under ordinary circumstances, that 

 cannot fail, if fully confirmed, to make it one of the most popular 

 and desirable of explosive agents. The causes which render 

 gunpowder and nitro-glycerine so dangerous to handle, or convey 

 by the common modes of transit, have no effect upon it. Nitro- 

 glycerine explodes at 240" F. ; gun-cotton at 400 degrees ; 

 gunpowder at 600 degrees ; a common fire at 1,200 degrees ; but 

 a much higher temperature than this is required to ignite dyna- 

 mite, which must be placed somewhere between 1,400 and 3,280 

 degrees. A thin deal box containing 10 pounds of the compound 

 was placed over a raging fire ; the box was consumed, but there 

 was no explosion, and the dynamite mingled harmlessly with the 

 ashes. It was in other ways placed in immediate contact with 

 fire, with the same results. Gunpowder was exploded near it 

 without effect. The superiority of the material over the danger- 

 ous explosives as to which concussion would be certain destruction 

 was acknowledged by several practical persons present, connected 

 with the carrying trades. Ten pounds of dynamite were enclosed 

 in a second deal box, and hurled from the top of a cliff. It fell 

 60 feet upon the rocks below, with no more signs of explosion 

 than would be caused by the fall of a brickbat. Equally striking 

 were the illustrations given of its deadly strength. A cartridge 

 filled with dynamite was placed upon a 2-inch oak plank. A 

 fuse with a strong percussion-cap was attached to it and fired, and 

 the plank was split in several places, and had a hole knocked 

 through it. The percussion-cap is the explosive agent, and it is 

 claimed that nothing else, so far as is known, will do the work. 

 In this instance the work was done most effectually, although the 

 cartridge, which was about the size of a man's finger, was laid 

 loosely on the plank. A large block of granite, about a yard 

 cube, was shivered by like treatment. A block of wrought iron, 

 with an inch bore-hole, but without either plug or tamping, shared 

 the same fate, as did a wrought-iron cylinder with a charge laid 

 loose on the top. The rocks Avere bored 15 feet deep, and 

 fired, with an effect that startled the quarrymen present, not be- 

 cause of the loudness of the report, so much as the immediate and 

 extensive character of the blasting. Other experiments demon- 

 strated the great velocity imparted to fragments of shells charged 

 with dynamite, and its adaptability to distress signals. 



Of the properties of this substance, Nobel mentions the follow- 

 ing : It burns in an open space, or, as commonly packed, without 

 explosion ; in burning in the air it evolves some nitrous fumes, 

 while in exploding, the products of combustion are carbonic acid, 

 nitrogen, and water, — all innocuous gases, — and no smoke, and it 

 leaves some white asiies. Moisture does not injure it ; it is some- 

 what poisonous, but by no means in the same degi-ee with nitro- 

 glycerine. In a closed space, with considerable power of resist- 

 ance of the walls, it is exploded by the spark, and in all cases only 

 by artificial heat. 



Its advantages over the ordinary blasting powder are saving 



