The New Student's Reference Work/Blasting

Blasting, the method of loosening or breaking in pieces masses of rock by means of the explosion of gunpowder or dynamite. It is used in sinking shafts, cutting tunnels, building roads and railroads and clearing channels. Formerly a form of slow burning gunpowder was used, but in 1868 nitroglycerine was used for the first time in boring the Hoosac tunnel. Now similar high explosives are universally used for blasting. Nitroglycerine is an explosive chemical compound made by treating glycerine with nitric and sulphuric acids. It is often mixed with an absorbent material, as sawdust, and dynamite is a general term for high explosives of this kind. The explosive is placed in holes which are drilled in the rock by hand or power drills, and exploded either by slow burning fuses or more generally by an electric spark. The removal of Flood Rock at Hell Gate in the East River, New York, October, 1885, was done by this method, and was the largest blast ever made. The rock covered about nine acres, 21,669 feet of tunnel were made, over 40,000 pounds of high explosives were used, and 80,232 cubic yards of rock excavated.