=Bone Department.=--The bone department is where the bones are cared for and prepared for commercial purposes. Nearly all bones that are of value, to be sold as such, come from cattle, and to this department is sent the horns, skulls, jaws, feet, shank bones, thigh bones, blade bones, rib bones and those resulting from cutting and boning cattle. These yield what is known as manufacturing bone, such as shins, blades, buttocks and thigh bones. Most of the balance is used for bone fertilizer, glue and grinding. The bone usually produced in the bone department is hard bone. =Hard Bone.=--Hard bones are those not cooked sufficiently to extract the glue stock, but enough to remove all grease. They are cooked in open vats. Excessive boiling brings the bones out in what is known to the trade as a “chalky condition” and injures the quality. =Glue Bones.=--Bones used for glue stock are green bones just as taken from the animal, or dried hard bone. In the former case the bone is crushed green, washed, boiled, and the liquor collected, filtered and evaporated. The residue is dried and is the article of commerce sold under the heading of “Steam Bone,” used extensively in fertilizer manufacturing. Those who slaughter on a moderate scale are usually not in a position to undertake the manufacture of glue. Consequently they are most interested in proper methods of manufacturing hard bones. =Bone Products.=--Small bones are also converted into bone charcoal, which is largely used for the purpose of bleaching sugar and in various medicinal preparations. Bones are used for a great variety of purposes, including the manufacture of bone charcoal for bleaching, empyreumatic oils; tallow; black pigment for painting, shoe blacking and filling sheet rubber for overshoes; bone dust for manure; sulphate of ammonia; cupels; vitrified bone of use in making opal glass, and in the manufacture of knife-handles, combs, fans, buttons, etc. Bones also furnish gelatine and glue, and are the starting point for the manufacture of phosphorus.