Everything is finished except the fumigant. I added the water but the other stuff will not work. Yes, the fire is going.

Did you close the door of the coal chamber?

Move your cursor over the pot to see exactly what's in there. Are there any other ingredients left over from earlier in the game?

The still says only water. How do I empty it so I can start over? thanks

The still can't be emptied, unfortunately.

Is this the first time that you've made the smokescreen - or did you make it earlier in the game? - In which case Saturnin would already have taken it when you spoke to him last, so it would not need to be made again.

Do you still have the iron box in your inventory?