~8. Bone Oil~ is made from the fat obtained by boiling the bones of animals. The finest quality is obtained from the leg bones of recently killed, healthy, young cattle, and the best method of treatment is given as follows[2]: "Fill a bottle one third full of the oil to be purified. Then pour clarified benzine in small portions upon the oil, close the bottle and shake until the benzine has disappeared. By again adding benzine and shaking, a complete solution of the fat is finally effected. That this has actually taken place is recognized by the contents of the bottle not separating after long standing. The bottle is then exposed to a low temperature for several hours, a 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 bone oil in the retort." (66.) ~9. Neat's-foot Oil~ is largely used in the arts, being one of the best of lubricants. The best oil, viz.: that used for clocks etc., is extracted by placing the thoroughly cleaned feet of cattle in a covered vessel near the fire or in the sun. The oil thus obtained is clarified by standing before bottling. (67.) It was the practice of many olden time watchmakers to allow a large bottle of neat's-foot oil to stand in a position exposed to the direct rays of the sun in summer and to the extreme cold of the winter. Then after two or three years, on a very cold winter day, to pour off such oil as still remained fluid which was preserved for use. ~10. Olive Oil~ has been used as a lubricant since the early days of horology, the older writers giving many methods of treating it. It is obtained from the fruit of the _Olea Europea_, one of the jasmines, which grows throughout Southern Europe and Northern Africa and other tropical countries. [Illustration: _Fig. 2.--A $25,000 Catch of Blackfish._] For the preparation of the finest oils, known as "Virgin oil," only the pulp of olives picked by hand is used. The pulp is packed in strong linen and the oil is expressed by twisting the linen together. The pulp sometimes contains as high as 70 per cent of oil. Its last traces of adhering acid are removed by rigorous and repeated shaking with one hundredth part of their weight of caustic soda lye. After the mixture has stood for several days a large quantity of water is added and the oil floating on the top is poured off.