Fragments of three white cast iron grenades with accompanied encrustration, recovered from a sunken wreck, the machault in the gulf of st. Lawrence, were examined. Results were obtained on the identification and characterization of material, determination and interpretation of its structure and composition, determination of the mode and extent of corrosion and reason for one grenade's failure; the method of manufacture and the mechanism of corrosion were also considered. Examination procedures included: visual observation; density measurements; chemical analysis; hardness testing; macroscopic and microscopic examination. Drawings, photomicrographs, references.