This is the softer portion of the purest and ireshest beef suet from the ribs, rendered at 140° F. to 150° F., arid the fat poured off clean and pressed at 95° F. The product is of a buttery consistency at ordinary temperature. The "oleo " oil, as it is called, is the chief constituent in margarine, bat a vegetable oil is also employed; sometimes this is cottonseed oil, at others earth nut oil or sesame oil. The oleo oil is melted and, along with the vegetable oil. is run into the churns; the milk is first soured by the addition of acid, rennet, or sour milk, run over cooling coils, and then into the churn. The churns are kept slightly warm, and are worked so that the fat, casein, etc., may amalgamate. They are then emptied into tanks containing water cooled with ice, the masses of fat are removed, piled up to drain for some time, then worked and salted like butter.