EXPLOSIVES. 
By Maj. Epwarp P. O’HeErn, 
Ordnance Department, United States Army. 
[With 7 plates. ] 
IMPORTANCE. 
The importance of the so-called explosives and the increasing 
extent of their use are evident from the fact that the production in the 
United States for the year 1910, as shown by the United States 
Census reports, amounted to the enormous total of approximately 
480,000,000 pounds, this being more than double the production of 
1905, and more than three and one-half times that of 1900. 
The increasing demand has come, not only from an ever widening 
field of commercial use, such as for mining, quarrying, tunneling, and 
road building, but from a greatly enlarged field of use for war purposes, 
such as for mines, torpedoes, explosive projectiles, and propelling 
charges. It is the purpose of the writer to discuss some of the more 
important explosives, their uses, the method of their employment, 
and the results accomplished. 
GENERAL CHARACTER. 
An explosive is a substance of which the molecules are made up of a 
number of atoms or units rather loosely bound together in an unstable 
condition, ready to seek new and simpler combinations upon the 
furnishing of a sufficient motive force to start the operation. This is 
usually supphed through a primer ignited by a slow-burning fuse, or 
by a wire heated by an electric current. When started, the heat and 
shock developed will cause a continuation of the action throughout 
the mass of the explosive. The enormous power that can thus be 
developed from a comparatively small quantity of material is indi- 
cated by the accompanying ilustration showing the thousands of 
fragments into which a 12-inch armor-piercing projectile was broken 
by the detonation of a bursting charge of about 53 per cent of its 
weight (pl. 1). 
TYPES OF EXPLOSIVES. 
For convenience of consideration, explosives may be divided into 
three general classes, viz: 
1. Progressive or propelling explosives (low explosives). 
2. Detonating explosives (high explosives). 
3. Detonators (fulminates). 
