Fractionation still
The Fractionation still is outside the north-west corner of the Chemist's house in western Rimmington. It is "a still for fractionating oils".
It is required in the Regicide and Mourning's Ends Part I quests to change a Barrel of coal-tar to a Barrel of naphtha.
How to use Fractionation still
First, Use the barrel of coal-tar with the Fractionation still.
Then, click the right side of the valve to the right twice, so the tar should be flowing at maximum. You should see the 'pressure' indicator on the left go up. When the indicator reaches the green region, click the right side of the valve on the left once to let out pressure. This should stall the indicator on the left. Now you can start adding coal (you need 6-8 per barrel). This will raise the indicator on the right. If it's below the green region, add more coal. If it's above, don't add coal until it gets lower. The bar on the bottom will start turning green, when it's full you can stop adding coal and close the window on the top right to get your barrel of naphtha.
