On the way home ours was the only car on the road, no sign of the bright lights and activity usual for this hour, and the smell of gunpowder had begun to fill the air.

回家的路上就只有我们一辆车在路上跑了，根本看到平日此刻的灯火通明和繁华，空气中弥漫着硝烟的味道。

youdao

Should others try to change our decision with force, they will smell southern gunpowder and feel the steel of southern swords."

VOA: special.2009.07.23

One somewhat practical application, they say, might also be for game play, where, say, a shooting game could be programmed to release the smell of gunpowder.

CNN: Apparently This Matters: Smell-O-Vision for your phone