4. Light a small piece of paper, and uncovering the
top of the chimney quickly drop in the lighted paper.
What happens?
What do these experiments indicate? What element
in air is necessary to a burning candle?
5. Clean two half-pint milk bottles. Insert a lighted
paper into one of the bottles and then cover. Pour a little
clear lime water into the bottle. Is there any change in
the clearness of the lime water?
6. Breathe into fresh lime water in the second bottle,
through a straw. Is the result similar to that of Exp. 5?
Clear lime water turns milky when carbon dioxide gas
mixes with it. Is any of this gas present in Exneriments
5 and 6? If so, explain where it came from.
Things Essential for a Fire. — Three things are essen-
tial for fire (1) air (oxygen), (2) fuel, and (3) a means of
raising- the temperature to the kindling point.
Oxidation (Combustion). — Oxygen unites readily with
many other elements, and the process is called oxidation.
When this takes place so rapidly that heat and light are
produced as in fire, we call it combustion. It may also
go on very slowly, yet the results are the same. Food is
oxidized slowly in every living cell of the body, giving
heat and the energy to do work.
The Kindling Point. — By the kindling point of a sub-
stance we mean the lowest temperature at which it burns,
or unites with oxygen. Fuels differ as to this temperature,
some having a much lower kindling point than others.
For this reason, matches, paper, and wood burn more
HEAT, COMBUS^TION, FUEL 29
readily than coal. The phosphorus of the match is ignited
by the friction of striking, and burns. This in turn is
used to ignite larger pieces of wood which have a higher
kindling point. In the making of a coal fire, wood is used
to raise the temperature high enough to ignite the coal.
Products of Combustion. — The most common products
of combustion are steam, carbon dioxide gas, smoke, soot,
and ashes. In incomplete combustion a gas is formed,
called carbon monoxide, which is very harmful to breathe.
The carbon that is not burned passes off as smoke and
soot. Soot contains some oily substances and sticks to
cooking utensils and to the chimney and should be removed
often. When allowed to accumulate in the chimney, soot
is apt to cause fires.
FUELS
The most common fuels are wood, coal, kerosene, and
gas. Being of vegetable origin, they all contain carbon.
Wood is either hard or soft. Soft wood kindles quickly
and produces a quick fire but which is of short duration.
Pine and birch are soft wood. Hard wood burns more
slowly, but a fire of hard wood keeps longer than one of
soft wood. Oak and maple are examples of hard wood.
Coal is of many kinds and is all formed from ancient
vegetation which has been buried deep in the earth for a
long time and subjected to a high degree of heat and pres-
sure. Coal has a higher kindling point than wood,
burns with a strong, steady heat for a long time, and holds
fire much longer than the hardest wood.
Kerosene, or coal oil, is prepared from petroleum and
is used in stoves made especially for it. It is a cheap fuel
and is safe if a good grade is used and care taken to keep
the stove clean and in good condition.
30 DOMESTIC SCIENCE
Page 17
Presented as published in 1914. Historical recipes may not meet modern food-safety standards. Cook from the modern interpretation, not the original instructions.
AI-modernized reading of the original text
4. Light a small piece of paper, and uncovering the top of the chimney quickly drop in the lighted paper. What happens?
What do these experiments indicate? What element in air is necessary to a burning candle?
5. Clean two half-pint milk bottles. Insert a lighted paper into one of the bottles and then cover. Pour a little clear lime water into the bottle. Is there any change in the clearness of the lime water?
6. Breathe into fresh lime water in the second bottle, through a straw. Is the result similar to that of Exp. 5?
Clear lime water turns milky when carbon dioxide gas mixes with it. Is any of this gas present in Experiments 5 and 6? If so, explain where it came from.
Things Essential for a Fire. — Three things are essential for fire (1) air (oxygen), (2) fuel, and (3) a means of raising- the temperature to the kindling point.
Oxidation (Combustion). — Oxygen unites readily with many other elements, and the process is called oxidation. When this takes place so rapidly that heat and light are produced as in fire, we call it combustion. It may also go on very slowly, yet the results are the same. Food is oxidized slowly in every living cell of the body, giving heat and the energy to do work.
The Kindling Point. — By the kindling point of a substance we mean the lowest temperature at which it burns, or unites with oxygen. Fuels differ as to this temperature, some having a much lower kindling point than others. For this reason, matches, paper, and wood burn more
HEAT, COMBUSTION, FUEL 29
readily than coal. The phosphorus of the match is ignited by the friction of striking, and burns. This in turn is used to ignite larger pieces of wood which have a higher kindling point. In the making of a coal fire, wood is used to raise the temperature high enough to ignite the coal.
Products of Combustion. — The most common products of combustion are steam, carbon dioxide gas, smoke, soot, and ashes. In incomplete combustion a gas is formed, called carbon monoxide, which is very harmful to breathe. The carbon that is not burned passes off as smoke and soot. Soot contains some oily substances and sticks to cooking utensils and to the chimney and should be removed often. When allowed to accumulate in the chimney, soot is apt to cause fires.
FUELS
The most common fuels are wood, coal, kerosene, and gas. Being of vegetable origin, they all contain carbon.
Wood is either hard or soft. Soft wood kindles quickly and produces a quick fire but which is of short duration. Pine and birch are soft wood. Hard wood burns more slowly, but a fire of hard wood keeps longer than one of soft wood. Oak and maple are examples of hard wood.
Coal is of many kinds and is all formed from ancient vegetation which has been buried deep in the earth for a long time and subjected to a high degree of heat and pressure. Coal has a higher kindling point than wood, burns with a strong, steady heat for a long time, and holds fire much longer than the hardest wood.
Kerosene, or coal oil, is prepared from petroleum and is used in stoves made especially for it. It is a cheap fuel and is safe if a good grade is used and care taken to keep the stove clean and in good condition.