Had little problem with this but you saved before you tried the mixtures yes?
I found that I had to dispose of the Smith first (then quick save) then move the coal over the salt (or was it the other way round) then add the sulfur - these -do- move between characters (DK and your Hero) so keep trying eventually you will end up with the explosive. Should you get confused you can always Ctrl-L (quick load) and try again.
I always let the imp go (poor might).
marts
