Everywhere in a large city or in a small village, smoke is seen,
indicating the presence of fire; hence there must exist a large supply
of oxygen to keep all the fires alive. The supply of oxygen needed
for the fires of the world comes largely from the atmosphere.
37. Matches. The burning material is ordinarily set on fire by
matches, thin strips of wood tipped with sulphur or phosphorus, or
both. Phosphorus can unite with oxygen at a fairly low temperature,
and if phosphorus is rubbed against a rough surface, the friction
produced will raise the temperature of the phosphorus to a point where
it can combine with oxygen. The burning phosphorus kindles the wood of
the match, and from the burning match the fire is kindled. If you want
to convince yourself that friction produces heat, rub a cent
vigorously against your coat and note that the cent becomes warm.
Matches have been in use less than a hundred years. Primitive man
kindled his camp fire by rubbing pieces of dry wood together until
they took fire, and this method is said to be used among some isolated
distant tribes at the present time. A later and easier way was to
strike flint and steel together and to catch the spark thus produced
on tinder or dry fungus. Within the memory of some persons now living,
the tinder box was a valuable asset to the home, particularly in the
pioneer regions of the West.
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