9Q HOW CROPS GROW. 
as minute, transparent globules in the cells, fi From 
these seeds the oil may be completely extracted by ether, 
= =» benzine, or sulphide of carbon, 
which dissolve all fats with readi- 
ness, but scarcely affect the other 
vegetable principles. 
Many plants yield small quan- 
tities of wax, which either 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 
Fig. 17. and wax, (Arendt). Scarcely two 
of these oils, fats, or kinds of wax, are exactly alike in 
their properties. They differ more or less in taste, odor, 
and consistency, as well as in their chemical composition. 
Exp. 89—Place a handful of fine and fresh corn or oat meal which has 
been. dried for an hour or so at a heat not exceeding 212°, in a bottle. 
Pour on twice its bulk of ether, cork tightly, and agitate frequently for 
half an hour. Drain off the liquid (filter, if need be) into a clean porce- 
lain dish, and allow the ether to evaporate. A yellowish oil remains, 
which, by gently warming for some time, loses the smell of ether and 
becomes quite pure. 
The fatty oils must not be confounded with the ethereal, 
essential, or volatile oils. The former do not evaporate 
except at a high temperature, and when brought upon 
paper leave a permanent “ grease-spot.” The latter readily 
volatilize, leaving no trace of their presence. The former, 
when pure, are without smell or taste. The latter usually 
possess marked odors, which adapt many of them to use 
as perfumes. . 
In the animal body, fat (in some insects, wax,) is formed 
or appropriated from the food, and accumulates in consid- 
erable quantities. How to feed an animal so as to cause 
the most rapid and economical fattening is one of the 
most important questions of agricultural chemistry, 
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