Explosives are frequently used in preparing foundations for buildings. It is also necessary, at* times, to do more or less blasting in connection with demolition operations, although this should be avoided as far as possible. When explosives of any kind are used they should be put in charge of some one person who is known to be experienced and thoroughly trustworthy, and who should be held responsible for the exercise of all possible precautions in connection with the storage and use of them.

A cool, dry place, protected from fire and lightning, is essential for the storage of explosives. If a considerable quantity is kept on hand a special storage magazine should be provided, but it is unlikely that the amount ordinarily required for building operations will necessitate a special storage place of this kind.

Never use steel or iron tools for opening boxes of dynamite. If the covers of the boxes are nailed on, use a hard-wood wedge and a wooden mallet, or a copper chisel. If the covers are secured with screws, use a screw-driver only for opening the boxes. Only as many cartridges as are needed for immediate use should be removed from the box, and the cartridges should be carried to the work in a dry box or bucket. Let somebody else carry the tamping stick, fuse (if fuse is used), and detonators - especially the detonators. The shot holes should be made ready before the dynamite is brought to the work, and the operations of priming, charging, tamping, and firing should be carried on as rapidly as is consistent with careful work.

Dynamite should never be used while frozen or partly-frozen, and sticks of it should never be slit, bent, kneaded, or otherwise manipulated while in this condition. Frozen dynamite should be carefully thawed in special thawing kettles heated by warm water, or in some other safe and approved way. It is highly dangerous to thaw dynamite by warming it in front of a fire, or by placing it in ovens, or on shelves over stoves or steam radiators.

Electrical shot-firing is to be preferred, because the charge can then be set off at any distance desired, the firing instant can be exactly determined, and accidents due to retarded and premature firing are largely eliminated. If fuse is used, it should be in first-class condition, and should not be brittle nor defective in any way whatsoever. Damaged or inferior fuse often causes blasts to be premature, or to be delayed. Blasting caps should always be fastened to fuse by a crimping tool, specially made for the purpose. It is highly dangerous to use the teeth for this purpose, or to employ any other makeshift method. The caps should not be attached to the fuse in or near the storage house, and they should not be inserted in the cartridges until just before these are placed in the holes, ready for tamping.

The stemming (or tamping) should consist of clay or of loosely-shaken dry sand, so that no sparks may be produced. The tamping rods should be made wholly of wood. Steel or iron rods should never be employed, under any circumstances; and the wooden rods should never have iron ferrules, nor contain tacks or nails, nor have any other metal parts whatsoever.

When a shot is about to be fired, all persons who are near the place should receive ample warning, and the fuse should not be lighted until it is absolutely certain that every one has been warned, and that no one is in a dangerous position.

A charge that has misfired should not be approached for at least two hours, and it is safer to leave it for an entire day, before making an examination. No attempt should be made to fire a charge that has failed to explode the first time, nor to tamper with it in any way. A new hole should be drilled about two feet from the first one, and a fresh charge inserted in it and fired.

It is impossible, in the space here available, to describe all of the dangers that are associated with the use of explosives. Additional information concerning special points in connection with explosives will be furnished by the Engineering and Inspection Division of The Travelers Insurance Company, upon request.