XII. 



CEOPS 



243 



of oil. The " cake " left after expression of the oil forms a valuable 

 4 and much used feeding stuff, being very rich in protein and in phos- 

 phoric acid. 



Flax or Linseed (Linum usitatissimum) is grown either for seed 

 or fibre. For the former, a warm climate is generally best, and the 

 sowing is somewhat thin 25 to 30 Ib. per acre. For the latter, moist, 

 cooler countries are best, and the seeding is thicker about 100 Ib. per 

 acre. In America, a fair yield appears to be about 16 bushels (of 

 56 Ib. per bushel) of seed and about 2000 Ib. of straw. 



Linseed is chiefly valued for the oil which it contains 30 or 40 

 per cent while the cake left after the extraction of the oil is very 

 rich in nitrogenous and mineral matter and forms a valuable food for 

 cattle. Linseed oil absorbs oxygen from the air and is, perhaps, the 

 best type of a " drying " oil. It is extensively used in the manufacture 

 of paints and linoleum. 



Castor Seeds (Ricinus communis). The plant in warm countries 

 is a perennial and grows to a tree 20 or 30 ft. high. In cooler 

 climates, with winter frosts, it can only be grown as an annual. It 

 grows well in almost a ay soil, but best in a rich, sandy one. The 

 plants commence to bear when four or five months old. The seeds, 

 whose resemblance to a tick gave rise to the botanical name, are con- 

 tained in a woody capsule. The seeds vary much in size and colour, 

 . according to variety of plant, and usually contain about 50 per cent of 

 oil, which is largely used as a lubricant, for burning, as a medicine, 

 and in the manufacture of soap. The cake left after expressing the 

 oil is generally used as a manure, since it is very poisonous to animals. 

 Immunity, however, to the poison may be acquired, or the poisonous 

 materal, ricin, may be extracted from the cake and it may then be 

 used as a food. 



Sunflower (Helianthus annuus) is grown for poultry food or for 

 the sake of the oil which it contains. The plants attain a height of 

 10 or 12 ft., and the seed-heads are about 12 in. in diameter and 

 yield about half a pound of seed each. The seed contains a kernel 

 (about half its weight), which contains from 30 to 50 per cent of oil. 

 The oil is used as a substitute for olive oil in cookery, for making 

 soap, and has been employed in adulterating margarine. It is a semi- 

 drying oil and is not suitable, therefore, for lubricating purposes. The 

 cake left when the oil is expressed from the seed is a valuable cattle food. 



The following analyses show trie average composition of some of 

 these seeds : 



