Percolation is an older method of making tinctures, popular with botanical pharmacists and physicians in the 1800s. The old Pharmacopoeias and Formularies (now available online) still preserve their instructions and recipes. The plant material to be extracted is dried, powdered, pre-soaked in menstruum, then carefully packed into percolation cones. More menstruum is added on top, and allowed to slowly drip (percolate) down through the plant material. This results in a thorough extraction with a rich concentration of active constituents.