Bone grease may be bleached by adding sulphuric acid and then thoroughly washing in water. Use two tanks, line 1 with lead, one above the other, and fitted with agitating gear; the lower tank should be fitted with a perforated steam coil. The melted grease is first run into the upper tank, and for each 10gal. l1b. to1 1/2lb. of strong sulphuric acid is added, and quickly agitated with the grease for about half an hour. The grease is then run into the lower tank, in which it is thoroughly washed with several lots of hot water and steamed. After settling, to further clear it the purified grease may be run off into a tank kept in a warm place, or the grease may be run into barrels if the presence of a small quantity of water is not detrimental.