After the oil has settled throw in about fifteen to twenty pounds of fine salt, scattering it thoroughly over the surface of the oil, the salt having the effect of carrying with it any unsettled tissues which may still remain in the oil. The top of the oil should then be carefully skimmed, for there is a scum floating on the top when it is settled. After this is done the siphon pipe is dropped down into the oil and the oil is taken off very carefully. It is very essential in drawing this with the siphon pipe that as little scrap and water as possible be taken with it. After the oil has been taken off, the bottom valve of the melting kettle is opened, dropping the contents into the scrap vat. The kettle should be thoroughly washed and cleaned before it is used again. _Ninth._--The oil now in the clarifier should be kept at a temperature of about 140° F. It should be allowed to remain in the clarifying kettle about an hour, and during this time should lose about ten degrees in temperature, perfect settling being possible only by lowering the temperature of the material. While oil is in the clarifier, sprinkle about four pounds of salt over it. As soon as it is settled skim immediately, and again a second time before the oil is drained into seeding truck. It should be drawn off into the seeding truck at a temperature of 120° to 125° F., care being taken at all times in siphoning the oil from the different kettles to see that no water has gotten into the oil. As it is impossible to draw the oil all out of the different kettles with the siphon, the oil that is left in the bottom of the kettle each time should be taken back and put into the melting kettle and allowed to run through with the next melting of fat. _Tenth._--Be particular to have the kettles washed each time after being emptied and see that they are kept at proper heat to receive each lot of fat when ready. _Eleventh._--See that all water, siphon pipes, and drawing-off pipes to the seeders be thoroughly scalded and steamed out before drawing, as there is invariably an accumulation in these pipes, which, if allowed to go uncared for, will turn rancid and injure the quality of the oil. CHAPTER XIII. BONE DEPARTMENT. BONE DEPARTMENT -- HARD BONE -- GLUE BONE -- BONE PRODUCTS -- HORNS -- MANUFACTURED ARTICLES -- SKULLS -- TEST YIELD FROM SKULLS AND FEET -- BUTTOCKS AND THIGHS -- BLADES AND RIBS -- DRYING -- CRUSHED BONE -- GRINDING BONE -- NEATS FOOT OIL STORAGE -- NEATS FOOT OIL PURIFIER -- YIELD TESTS.