GUN-COTTON FOR BLASTING PURPOSES.

Grey River Argus, Volume VII, Issue 505, 10 April 1869, Page 3

GUN-COTTON FOR BLASTING PURPOSES.

Gun-cotton as a substitute for blasting- . powder in mining operations seems to possess a great number of advantages, and to fully deserve the good opinions which have been expressed as to its capabilities. Some Late experiments made with it by Mr H. A. Thompson prove conclusively that the cim-cotcon is more powerful, more economical, more effective, and leas dangerous than the ordinary blastingpowder. Its special advantages, as cetailod by Mr Thompson, are that it occupies less space, nnd thus saves labor, as borings only a third of the depth required for blasting-powder are needed ; that the effect is greater, the rock being shattered all round the bore ; that no smoke proceeds from it ; and that it is more manageable than the powder. With reference to the alleged danger of exploding the guncotton while tamping the. hole, Mr Thompson remarks that a little cave jtrevents any risk of that kind. When placed upon an anvil, and struck by a hammer, the cotton explodes readily, but when placed upon wood, stone, or brick, and struck with a wooden mallet, it cannot be explociel at all. The tamping of the holes with a wooden tamping bar is, therefore, an effectual, preventative of premature explosions. An inch cartridge of the cotton is equal to two ounces .and a half of good blasting-powder, when used in rock of medium hardness. But the. proportions vary with the character of the rock ; and Avhere the stone is broken up by numerous joints, ' blasting-powder has more effect than cotton. Exploding the cotton by percus- , sion increases its power by one-half or two fifths, and therefore a much greater effect is produced if a little blastingpowder is laid on the top of the" charge of cotton to fire it. Several trials of this system were made by Mr Thompson, and the result proved that a reduced quantity of cotton with blasting-powder to fire it, did equal or better work than the full charge fired in the ordinary way. The method recommended by Mr Thompson is to put half an ounce to an ounce of blasting-powder in a piece of calico, and' tie it to the fuse, the end of which is inserted in the powder. , This is placed on the top of the cotton instead of wadding ; the hole is then tamped and fired as usual. ; —Argus.