BLASTING- AT THE BLUE SPUR.

Tuapeka Times, Volume II, Issue 56, 6 March 1869, Page 5

BLASTING- AT THE BLUE SPUR.

(EROM A CORBESPONDENS 1 ). The extent of blasting operation* on the Blue Spur render aU improvements in explosive agente, and the methods of " \wp~\thoai effectually, of deep interest to i9JM|ters generally. Upwards of forty toflKt blasting powder annually are used by the different mining companies here, in large and email blaste. For some time great hopes were entertained that nitroglycerine would tome inter general use, and effect c great earing of labous and money in heavy blasting. Ite chief recommendation was based upon its immense explosive strength, and small bulk, in comparison with blasting powder. Unfortunately, however, the danger attending the use and transport of nitro-glycerine and the terrible loss of life and property occasioned by premature explosions, have proved it a compound too dangerous for general use. Gun-cottoft has long been known ea en explosive agent, but from various cause* it hae been little used — - but recently it has been discovered to have »trength equal to nitro-glycerin«, when exploded by concussion ; and at no distant day, when its properties are generally understood and the method of using it is familiar to miners, it is likely to ■supersede blasting powder altogether. Already it is used with marked success on come of the quart* reefs in Victoria", and is highly appreciated by the miners. )K Many improvements have been applied to heavy blasting, since the practice was nrst Applied to mining on the Blue Spur by Messrs. Morrison and Co., four years ago. At firet galvanic batteries were used ~to . fire the charges of powder, but it was Boon found that they were too expensive' and uncertain in action for general use> and the* were altogether abandoned in favor of the common fuse. The practice ionnerly wrvs to deposit the charge of powder in a large wooden case, made water-tight by tawing the joints, and the { TOre or fuse was invested in the powder through a email hole in the case, and the blast wae £*ed after the tunnel was tightly tamped with clay ; but now a keg of powder is generally opened for each chamber, and a train of powder in wooden piping is connected with each keg ; and the fusd for firing tlie blast i« inserted in the train and carried towards the mouth , «J the tunnel to be lighted when the tamping is completed. The bulk of the powder is deposited in the kegs unopened above and around the opened kegs in each chamber, and it is found that the - whole charge explodes simultaneously with the contents of the opened kegs.JQf - the tunnel or chambers are wet, large etones or block* of cement are placed in the bottom of the tunnel ac the tamping | goes on, and the drainage-water escapes without damaging the powder. It has been proved by e'-^-c-ricUv.-* i\*.' tight l^g. ' lamped enfir*!/ -with lar^e vitoaes I M)!Tj>*a of cement without impairing L^ 3 effect of tke'eiplosion. Grea* care is — • Tequwed in connecting the fuse i?\th the powder in the train-, for unless the fu.vtouches the powder, a laiss-fire may be the result, and the tamping have to be taken out at considerable risk to life. About three yeass ago Livingston and Go. had a miss-fire, and after clearing back the tamping, they found tha ends of the fuse at the train had curved upwards, and the jet of fire had burnt the wooden pipe without igniting the powder. Most of the accidents -which, happen in blasting with, drill-holes occur through miss-fires. A mise-nre rarely happens if good fuse is used, and the end of the fuse - is freshly cut and properly inserted in the powder before the tamping is commenced. When a miss-fire takes place the safest plan is, if the tamping hae to be taken ont, to use plenty of water and ke«»p the tamping wet, which prevents the sparks [ occasioned by friction from exploding the charge. By this plan the powder is rendered non-explosive, and destroyed ; whereas an attempt to take out the tamping dry and save the powder involves a risk that no one who valued life or limb ought to run.