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IX. PLANTS CULTIVATED FOR THEIR OILS. 



THE plants most generally cultivated for their oils, are, 1. 

 The rape, and other plants of the cabbage genus. 2. The mus- 

 tard and radish. 3. Hemp and flax. 4. The poppy. The 

 oils which these plants yield, are obtained by bruising or crush- 

 ing their seeds, which operation is performed in a great variety 

 of ways they are termed fixed oils. There is another class of 

 oils obtained by distillation, termed volatile oils. These last 

 are yielded mostly by plants of the mint family but the plants 

 producing them are rarely the subjects of cultivation on the 

 large scale. Our chief oil plant is the flax. The growing of 

 the oil plants form an important part of the agriculture of 

 many countries. 



The method of cultivating this plant -the flax for its fibre, 

 has been pretty fully described; and there is no other difference 

 in the manner of cultivating it for its seeds, than permitting the 

 plant to stand until the seeds are fully ripe. The seeds are 

 bruised in the same manner as those of the other oleaginous 

 plants. The refuse, after expression, is termed oil-cake, and 

 forms a nutritive food for cattle. The mills used for bruising 

 the seeds in many parts of the country, are constructed on very 

 simple principles. More perfect machinery is necessary. The 

 seeds of hemp, in like manner, yield oil, which is employed 

 for nearly the same purposes as the oil of flax. But the pre- 

 paration of the flax and expression of the oil, should form a 

 distinct profession they do not of right belong to the labours 

 of the farm, although sanctioned by an almost universal prac- 

 tice. 



I. RAPE. 



Rape is now considered as the principal oil plant of Europe 

 and is cultivated on a very extensive scale, especially in Eng- 

 land, Holland, the Netherlands, Germany and France. It is 

 a plant admirably adapted to this country. About the year 

 1823 or 1824, an English gentleman cultivated it to some con- 

 siderable extent in the county of Philadelphia, but for some 

 reason, never yet fully explained, it was discountenanced by 

 our farmers. From one bushel of the seed a gallon of fine and 

 superior oil was extracted which sold readily for one dollar. 

 The manner of cultivating the rape has been already described. 

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