What is a case of strong paper filled with a composition of niter, sulphur, and mealed powder, -- used principally to ignite the priming in proving guns, and as an incendiary material in shells called?

portfire — A case of strong paper filled with a composition of niter, sulphur, and mealed powder, -- used principally to ignite the priming in proving guns, and as an incendiary material in shells. (Webster's 1913.)

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