Rapeseed (Colza) Oil: Ripened, Threshed and Pressed

Colza, or rape, is a cabbage relative whose small seeds give an oil that lit the lamps of France and Belgium. Andrew Ure (1839) notes the seed yields oil only in proportion to its ripeness, so the plants are cut a little early, before the pods shed, and left to finish ripening in heaps before threshing. The pressing is the same as for linseed oil. The picture: a rapeseed (colza) field in flower.