In moist air the powder ignites spontaneously, forming a mixture of products including some nitrogenous compounds.

If the powder did not ignite, the mixture had too much water in it and the proof was considered low.

Thinking it was perhaps a type of gunpowder, he tried to light it, but the powder would not ignite.

The match heads inside the fuse flared and the powder ignited and burned.

On Jan. 2 two students who were apparently trying to make small bombs were seriously injured when the explosive powder accidentally ignited.

"And after three or four times, the powder ignites, and a big flame shoots out."

The powder ignited along with the dry wood.

There was a novelty picture in it, when the powder slipped down his shirt and ignited and the others had to slap out the flames.

The drifting dhow had blown up as the powder in her magazine ignited.

While the British were trying to destroy it by dropping the barrels into a well, the powder ignited.