FIG. 64.—REVOLVING BONE WASHER.
Purifying Oil.
—The oil is kept in the containers until ready for purifying. The two receivers are connected together by a common pipe which terminates in a pipe arranged in the form of a cross with a tee connection at each end. Over the ends of this cross are suspended cotton flannel bags of double thickness tied tightly over the tees. The oil is strained through these into the purifier where it is settled for two or three hours. Should any moisture appear it is withdrawn at the drain cock at bottom. Bags should be used once and carefully washed. The oil is then dried out by heating the same through the steam jacket on kettle until it reaches a temperature of about 250° F., at which temperature it is held several hours. The oil is to be stirred occasionally during the drying period. The steam is closed and the oil allowed to settle and cool and is then put in casks. Temperature of oil when drawn into casks, about 80° to 90° F., casks, hard wood, well hooped and of superior quality to prevent leakage.
Neatsfoot Oil.
—Obtained from cooking round shin, flat shin, small knuckle bones (being bones from feet) and shin bones.
Finishing Bones.
—After taking the oil and depositing same in the neatsfoot oil receiver, the shin bones are removed and placed in the polisher where they are revolved for about one hour or until the bones are cleaned. Warmed water is passed through the bones during this process, introduced through hollow shaft in washer. The substance washed out contains more or less oil which should be trapped and the clear oil skimmed off, and balance of material sent to the rendering tanks. The knuckles are similarly treated until cleaned.
Drying Bones.
—When the shin bones are washed and cleaned they should be spread on racks to dry, in natural temperature (not coil dried) and out of draft or cold temperatures to avoid checking or splitting. Small knuckle bones from the feet are to be coil dried for manufacturing bone.