The boys were loaded with explosives.
Which they let off.
In his immediate personal neighborhood.
And he jumped.
And cursed Young America, as he had cursed it a thousand times before.
But there was no escape for him.
They improvised a band.
And they played Yankee Doodle.
And Hail Columbia.
--From A Quiet Fourth of July--
Notice that the boys appear to be shooting guns into the air:
So "explosives" probably is the proper term to use.
Here's Hail Columbia, which almost no one now-a-days could identify (We use it for Vice-Presidential entrances, poor thing!):
And here's Yankee Doodle:
Imagine people spontaneously playing this music, shooting off explosives, not standing passively watching a parade, and you will realize how much different the fourth of July used to be.