Ignition is the raising of the temperature of some point of a grain of powder to 300° C.
Inflammation is the spread of the ignition from point to point on the surface of the grain or mass.
Combustion is the burning of the grain from the ignited surface, inward or outward, as the case may be.
Density is the ratio of the weight of a grain of gunpowder to that of an equal volume of water under standard conditions. It varies from 1.68 to 1.90, rarely exceeding 1.85.
Gravimetric Density is the ratio of a given volume of powder to that of an equal volume of water under standard conditions.
Density of Loading is the ratio of the weight of a charge of gunpowder to the weight, under standard conditions, of the volume of water that would fill the powder-chamber. Its value is 27.68 W/C, in which W is the weight of the charge in pounds, and C the volume of the chamber in cubic inches.
Initial Air-space is the portion of the chamber in a loaded gun or shell unoccupied by solid matter before firing.
The Reduced Length of any volume in the bore of a gun is the height of a right cylinder of the same volume, but with a diameter equal to the calibre of the gun.
An Adiabatic Transformation is a change that takes place in the state of a gas within an envelope impermeable to heat, or which occurs in such a short space of time that no heat is received or lost by it.
Detonation is exceedingly quick explosion.