Note:  Do not rely on this information. It is very old.

Clearing Nut

Clearing Nut, the one seed in the fruit of Strychnos potatorum, a tree native to the forests of India, used in that country to purify turbid water by being simply rubbed round the inside of the drinking-vessel. This action depends apparently on the albumen and casein which the seed contains acting as a fining agent like the isinglass dissolved in acid employed in fining beer.