There are three main groups of oils: animal, vegetable and mineral." b, T- L* P8 D
Great numbers of animal oil come from whales, those enormous __1__! m' V. p9 L3 g# G3 b1 p
creatures of the sea which are the largest remaining animals in the) ?+ U1 H2 h" H6 O& L" m
world. To protect the whale from the cold of the Arctic seas, nature3 t0 Y" s( |) U: r- U* @. [& X7 q
has provided it with a thick cover of fat called blubber. When the __2__
1 Y$ p5 f, I( R2 a9 P, I whale is killed, the blubber is stripped off and boiled down, either4 t' ^" P8 A9 N5 k3 X
board the ship or on shore. It produces a great quantity of oil which __3__
, _# J R# r+ Z+ _ can be made into food for human consumption. A few other creatures7 f$ z1 x3 H' L: c6 [
yield oil, and none so much as the whale. The livers of the cod and __4__
; @3 [) Y. l# b the halibut, two kinds of fish, yield nourishing oil.
! Z/ X, ^, ^ @" |6 {7 f1 ] Both cod liver oil and halibut liver oil are given to sick children F; V$ a: I* n6 l% C4 }! d
and other invalids who need certain vitamins. These oils may be/ f& `9 ?+ Z! a, D* u; |
bought at any chemist. Vegetable oil has been known from antiquity. __5__8 O3 O# R1 V+ ~ B6 S$ R
No household can not get on without it, for it is used in cooking. To __6__# i# C( \- a( k0 O s2 E
the ordinary man, one kind of oil may be as important as another.
( \( Z9 c/ V7 u/ j( I3 F4 B But when the politician or the engineer refers to oil, one almost always __7__* {, ~6 P( H1 @+ D+ u
means mineral oil, the oil that drives tanks, aeroplanes and warships,
7 |. t. V2 h+ L& @( L" A motor-cars and diesel locomotives; the oil that is used to lubricate
' E# y1 ]% K! t0 { all kinds of machineries. This is the oil that has changed the life __8__# S7 x0 j2 p8 [8 w8 f6 ]
of the common men. To it we owe the existence of the motor-car, __9__2 }, C2 [; t% ?' d( ^
which has replaced the private horse-drawing carriage. __10__ |