"the faint tang of cordite coming up from the cellar"
Cordite is a smokeless propellant. It is produced in the form of rods of varying thicknesses by being pressed through perforations in a steel plate while in its soft, paste-like form by screw pressure, thus why it is called cordite. There are two types: Cordite Mark 1 and Cordite MD. The latter does not burn as quickly as the former. However, both types continue to burn even when the flame is blown out. Cordite is now obsolete and is no longer in production.
Cordite from World War II