Fats and fatty oils are purified by "breaking" with mineral acids, alkalies, or salts to remove mucilaginous and solid or colloidal matters, and then submitting to high vacuum short path distillation to remove free fatty acids and colouring matter as a first fraction and to leave a final residue of resinous and vegetable matter. The treatment of linseed, cottonseed, ground-nut, palm, and whale oils is specified. For example: (1) cottonseed oil is stirred for 1 hour at 80 DEG C. with 0,1 per cent of 50 per cent caustic soda, the mucilage separated by settling, filtering, or centrifuging, and the clear oil distilled under a vacuum of 10-3--10-4 m.m. of mercury in a still having the heating and condensing surfaces 1,5 cm. apart; the 5 per cent distilling off at 200--220 DEG C. is dark coloured and contains the free fatty acids; the 90 per cent distilling at 250--260 DEG C. is a water-white oil; the residual 5 per cent is a dark tarry mass. (2) Cottonseed oil is broken by stirring for 1 hour at 70 DEG C. with 0,1 per cent of 98 per cent sulphuric acid, the mucilage removed, and the oil fractioned as in example 1; 7 per cent distils off at about 210 DEG C., 90 per cent at 250--260 DEG C. Specification 415,088, and the prior treatment of cod-liver oil are referred to.
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