This section is from the "Henley's Twentieth Century Formulas Recipes Processes" encyclopedia, by Norman W. Henley and others.
Put 2,000 parts, by weight, of virgin oil in a decanting vessel, add a solution of 40 parts of ether tannin in 400 parts of water and shake until completely emulsified. Let stand for 8 days, with frequent shaking; next, add 100 parts of talcum and, when this has also been well shaken, 1,600 parts of water. Allow to settle for 24 hours, and then run off the lower water layer, repeating the washing as long as the wash water still shows a coloration with ferric chloride. Pour the contents of the decanting vessel into an evaporating dish; then add 200 parts of thoroughly dried and finely ground cooking salt; let stand for 24 hours and filter through paper. The clock oil is now ready, and should be filled in brown glass bottles, holding 20 to 25 parts (about 1 ounce), which must be corked up well and kept at a cool temperature.