Friction, Lubrication and the Lubricants in Horology

"[...]solid fat deposits on the bottom, and the lower the temperature the greater is the deposit. Alongside the bottle containing the oil, place another bottle with a funnel, the lower end of which is closed by a cotton stopper; after thoroughly shaking the bottle with oil, pour the contents into the funnel; the fluid portion runs into the bottle, while the solid portion is retained in the funnel by the cotton stopper. The clear solution of bone oil in benzine collected in the bottle is then brought into a small retort which is connected with a thoroughly cooled receiver. Place the retort in a tin vessel filled with water and apply heat. The benzine readily distills off, leaving the purified[...]".