Linseed,

Linseed, the seed of flax, largely imported from the Continent and India, for making linseed-oil and oil-cake. In making these the seeds are first bruised or crushed, then ground, and afterwards subjected to pressure in a hydraulic or screw press, sometimes without heat, and sometimes with the aid of a steam heat of about 200° (93.4° C.). Linseed-oil is usually amber-coloured, but when perfectly pure it is colourless. It has a peculiar and rather disagreeable odour and taste. It is chiefly used for making varnishes, paints, &c. That made without heat (cold-drawn linseed-oil) is purer, and less apt to become rancid, than that in making which heat is applied. By cold expression the seed yields from 18 to 20 per cent., and with heat from 22 to 27 per cent. of oil. Linseed-oil boiled, either alone or with litharge, white lead, or sulphate of zinc, dries much more rapidly on exposure to the air than the unboiled oil; and boiled or drying oil is particularly adapted for many uses.—The Oil-cake (q.v.) made in expressing linseed-oil is very useful for feeding cattle. Linseed itself is excellent food for cattle and for poultry. The seed coats abound in mucilage, which forms a thick jelly with hot water, and is very useful for fattening cattle.—Linseed-meal, much used for poultices, is generally made by grinding fresh oil-cake, but it is better if made by grinding the seed itself.