(n) :
a chemical used to track the progress or history of a natural process; a piece of ammunition for a firearm that contains magnesium or another flammable substance arranged such that it will burn and produce a visible trail when fired at night
(n) :
a chemical used to track the progress or history of a natural process; a piece of ammunition for a firearm that contains magnesium or another flammable substance arranged such that it will burn and produce a visible trail when fired at night