314 ECONOMIC BOTANY. 



panicles ; the stigmas are feathery and the capsules are 

 prickly. The seeds are the size of a small bean, with a 

 shell sprinkled brown and gray. They contain in the 

 endosperm a large quantity of albuminoids. The oil in 

 the seeds, for which the plant is cultivated, amounts to 

 forty or forty-five per cent. ; it is a thick fluid, of pale color, 

 slightly nauseating odor, and oily taste. It is used for illu- 

 mination, especially in the East ; it is employed in the manu- 

 facture of soap, and used in medicine as a mild cathartic. 



311. The Flax-plant, Linum usitatisaimum (described in 

 paragraph 261), is cultivated mainly for the fibre, but the 

 seed is also an important product, because of the oil which 

 is expressed from it. Each capsule has ten small brown 

 seeds, which are flattened, smooth, shining, and oblong. 

 These are found by analysis to contain eight per cent, of 

 water, thirty-three per cent, of oil (twenty-seven per cent, 

 being usually expressed), twenty-five per cent, of albumi- 



. noids, a trace of tannin, and four or five per cent, of ash. 

 The Flaxseed-oil is a drying oil, used in the manufacture 

 of printer's ink, varnishes, soap, and for food. 



312. For a long time the seeds of cotton, Gossypium 

 herhaceum, etc. (see paragraph 258), were regarded as 

 useless refuse, but from them lately an Oil has been ex- 

 pressed. The seeds, after the removal of the coating of 

 hairs (cotton), are seen to be oval, their cotyledons much 

 folded, and contain forty-five per cent, of oil, and grains of 

 aleurone. The oil has a specific gravity of .93 ; it contains 

 palmatin and oleic acid ; unrefined it is brownish ; refined 

 it is yellowish or whitish. It is used as a machine oil, 

 for illumination, and in the manufacture of soap, etc. 



313. The Chocolate-tree, of Tropical America, Theo- 

 broma cacao (family SterculiaceoB), is a small tree sixteen 



