Appearance and properties: colorless to pale yellow liquid, exposed to air can change color. 
 Main purpose: used as a drying oil in paints and varnishes, also used for the manufacture of drugs. 
 Linol of linoleic acid (e) ic acid, CH3 (CH2) 4CH = CHCH2CH = CH (CH2) 7COOH, a fatty acid. Glyceride form consisting of linseed oil, cottonseed oil and the like drying oil, semi-dry oil the main component. Accounted for 40-60% of the walnut oil, cottonseed oil, sunflower seed oil, sesame oil fatty acid, accounting for about 25% of the total fatty acids in walnut oil, peanut oil, olive oil. Easily oxidized in air to harden, also known as dry acid, with dry acid and more oil is also known as drying oils.