Possible Clues:

• Sea dog's safe-sounding meat preservative
• Part of explosive mixture shattering steel trap
• Sailor about to collect special gunpowder ingredient
• It's used as a fertilizer and explosive
• Ingredient of explosive soldier favoured in revolutionary times
• Explosive component to season: about to go past favourite
• Later step developed a constituent of gunpowder
• An ingredient of gunpowder later step developed
• Old sailor preferred dealing with explosive ingredient
• Potassium nitrate, often used as a preservative