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There are three main groups of oils: animal, vegetable and mineral.
Great numbers of animal oil come from whales, those enormous __1
creatures of the sea which are the largest remaining animals in the world. To protect the whale from the cold of the Arctic seas, nature has provided it with a thick cover of fat called blubber. When the __2
whale is killed, the blubber is stripped off and boiled down, either board the ship or on shore. It produces a great quantity of oil which __3
can be made into food for human consumption. A few other creatures yield oil, and none so much as the whale. The livers of the cod and __4
the halibut, two kinds of fish, yield nourishing oil.
Both cod liver oil and halibut liver oil are given to sick children and other invalids who need certain vitamins. These oils may be bought at any chemist. Vegetable oil has been known from antiquity. __5
No household can not get on without it, for it is used in cooking. To __6
the ordinary man, one kind of oil may be as important as another.
But when the politician or the engineer refers to oil, one almost always __7
means mineral oil, the oil that drives tanks, aeroplanes and warships,motor-cars and diesel locomotives; the oil that is used to lubricate all kinds of machineries. This is the oil that has changed the life __8
of the common men. To it we owe the existence of the motor-car, __9
which has replaced the private horse-drawing carriage. __10
