[Illustration: Field of Flax in bloom in North Dakota] Boiled linseed oil, a heavier and darker product, is made by heating the raw oil in open kettles to high temperatures, generally with the addition of metallic driers such as litharge, and black manganese. The resinates of lead and manganese are often added to oil heated at a lower temperature, to obtain a boiled oil of lighter color. [Illustration: New type of Flax Harvester which pulls plant up by the roots, thus preventing infection of soil] [Illustration: Modern Concrete Elevators for storing Flaxseed] [Illustration: View of Linseed Oil Factory showing hydraulic press, tanks, etc.] [Illustration: _Photographs courtesy of Spencer Kellogg Sons_ Flaxseed Crushers] [Illustration: Filter Presses for removing extraneous matter from linseed oil] [Illustration: Linseed Cake from Oil Press] [Illustration: Glycine Hispida Mammoth soya bean plants] [Illustration: _Photographs courtesy of David Fairchild, Plant Explorer, U. S. Dept. of Agriculture_ Glycine Hispida Soya bean plants under cultivation at Arlington, Va.] By blowing air through linseed oil that has been heated to approximately 200 degrees Fahrenheit, either with or without drier, heavy bodied oils are obtained, which find special application in varnishes and technical paints. As the viscosity of these oils increase, the iodine values decrease, and a slight rise in saponification value and specific gravity is observed. The following analyses of various types of linseed oil were recently made by the writer: