THE VOLATILE PART OF PLANTS. 



83 



effect on vegetable colors that belong to ammonia. Car- 

 bonate of sodium has the taste and other properties of caus- 

 tic soda in a greatly mitigated form. On the other hand, 

 sulphates of aluminum, iron, and copper, have slightly 

 acid characters. 



5. FATS AND OILS (WAX). We have only space here 

 to notice this important class of bodies in a very general 

 manner. In all plants and nearly all parts of plants we 

 find some representatives of this group ; but it is chiefly 

 in certain seeds that they occur most abundantly. Thus 

 the seeds of hemp, flax, colza, cotton, bayberry, peanut, 

 butternut, beech, hickory, almond, sunflower, etc., con- 

 tain 10 to 70 per -cent of oil, which may be in great part 

 removed by pressure. In some plants, as the common 

 bayberry and the tallow-tree of Nicaragua, the fat is 

 solid at ordinary temperatures, and must be extracted by 

 aid of heat ; while, in most cases, the fatty matter is 

 liquid. The cereal grains, especially oats and maize, con- 

 tain oil in appreciable quantity. The mode of occur- 

 rence of oil in plants is shown in Fig. 17, which repre- 

 sents a highly magnified section of the flax-seed. The 

 oil exists as minute, transparent globules in the cells,/. 

 From these seeds the oil may be completely extracted by 

 ether, benzine, or sulphide of car- 

 bon, which dissolve all fats with 

 readiness, but scarcely affect the 

 other vegetable principles. 



Many plants yield small quanti- 

 ties of wax, which often gives a 

 glossy coat to their leaves, or 

 forms a bloom upon their fruit. 

 The lower leaves of the oat-plant 

 at the time of blossom contain, in 

 the dry state, 10 per cent of fat 

 17 - and wax (Arendt). Scarcely two 



of these oils, fats, or kinds of wax, are exactly alike in 



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