Rare, literary, or historical term for gunpowder. In modern Japanese, 火薬 (かやく) is the standard word.
The smell of gunpowder hung over the battlefield.
Rare kanji spelling for gunpowder; the more common form is 火薬 (かやく).
Variant kanji spelling; even rarer than 煙硝.
The kanji 煙 (smoke) and 硝 (saltpeter) together suggest 'smoke-producing saltpeter', a descriptive term for gunpowder. The reading えんしょう is on'yomi. The exact historical derivation is uncertain.