of valuable fundamental information, so simply expressed as to be easily
understandable by coal miners, and yet sufficiently detailed to be a
valuable guide to all persons who have to handle or use explosives.

In the first chapters are described the various combustible substances,
and the chemical reactions leading to their explosibility. The low and
high explosives are differentiated, and the sensitiveness of fulminate
of mercury and other detonators is clearly pointed out. The various
explosives, such as gunpowder, black blasting powder, potassium chlorate
powders, nitro-glycerine powders, etc., are described, and their
peculiarities and suitability for different purposes are set forth. The
character and method of using the different explosives, both in opening
up work and in enclosed work in coal mines, follow, with information as
to the proper method of handling, transporting, storing, and thawing the
same. Then follow chapters on squibs, fuses, and detonators; on methods
of shooting coal off the solid; location of bore-holes; undercutting;
and the relative advantages of small and large charges, with
descriptions of proper methods of loading and firing the same. The
subjects of explosives for blasting in rock, firing machines, blasting
machines, and tests thereof, conclude the report.

The work of the chemical laboratory in which explosives are analyzed,
and in which mine gases and the gases produced by combustion of
explosives and explosions of coal-gas or coal dust are studied, has been
of the most fundamental and important character. The Government is
procuring a confidential record of the chemical composition and mode of
manufacture of all explosives, fuses, etc., which are on the market.
This information cannot but add greatly to the knowledge as to the
chemistry of explosives for use in mines, and will furnish the basis on
which remedial measures may be devised.