How do I get the chimney sweep's gold?

Hint 1 of 11:

In case you haven't noticed already, the chimney sweep has a gold brush. 
That's what you need to take from him.

Hint 2 of 11:

What you need to do here is create a little accident for him.

Hint 3 of 11:

Like a nice explosion, for example.

Hint 4 of 11:

You can find a keg of explosives in the crate next to the city gate.

Hint 5 of 11:

You first want to get the chimney sweep to come over to the chimney above
that fireplace and clean it, if he isn't there already.  (My copy of the game
had a bug where the sweep appeared to be in two locations at once, so I'm not
really sure where he's supposed to be.)