Flame. — When two substances unite chemically, and
both are gases or vapors at the temperature of combustion,
the act of union is accompanied by a flame. When one of
the substances remains solid at the temperature of combus-
tion, heat and light are given off, but there is no flame.
Many substances which are solids or liquids at ordinary
temperatures vaporize slowly when at the temperature of
burning and hence burn with a flame. The light given by
the flame is caused by the glowing, or incandescence, of the
solid carbon particles. At a higher temperature the carbon
10 DOMESTIC SCIENCE
is quickly and completely burned and gives no light, but
burns with a blue flame.
When gas is used as a fuel it is mixed with air before
burning, in order that it may be diluted, when there will be
a more perfect combustion. A gas used as fuel should burn
with a blue flame ; a yellow or a smoky flame indicates that
the carbon is not being completely consumed and there is an
attendant loss of heat.
NOTE. — Students examine carefully a Bunsen or other gas burner,
increasing and decreasing the supply of oxygen by opening and
closing the mixer. Note the varying color of the flame and the
seeming increase or loss of heat.
Kindling Point. — Every combustible solid must be raised
to a certain temperature, or kindling point, before it will
unite rapidly enough with oxygen to produce light. This
temperature varies with different substances, but is always
the same for the same substance. The kindling point of
phosphorus is very low. Ordinary parlor matches are tipped
with phosphorus, potassium chlorate, and glue. The heat
produced by the friction of striking the match is sufficient
to raise the phosphorus to its burning point. The heat
produced by the burning of the phosphorus raises the wood
of the match to its kindling point, and the match ignites.
NOTE. — Student explain the steps in fire building by which
hard coal may be raised to its kindling point.
Flash Point. — The temperature to which a fat or oil must
be raised before an inflammable vapor is given off is called
the flash point. This is a valuable indication of the safety
of an oil.
Fuels. — A fuel is a combustible substance usually com-
posed of carbon and hydrogen.
AIR AND COMBUSTION 11
NOTE. — Student prepare a list of fuels —
SOLIDS LIQUIDS GASES
NOTE. — Students inspect specimens of hard and soft woods ;
charcoal ; peat ; bituminous, anthracite, and cannel coal ; various
fuel oils ; alcohols.
Students write paper on the "Story of Coal."
Students procure the current market price of the various fuels
listed above. From the cost of a basket of coal or "bundle of
wood," estimate the price paid for a ton of coal and a cord of wood
when purchased in small quantities.
Heat. — Heat is molecular motion.
Sources of heat :
1. Mechanical energy.
Produced by friction or by collision.
2. Chemical energy.
Produced by combustion or by chemical union of dif-
ferent compounds or elements.
3. Electrical energy.
As produced by an electric toaster, etc., or by the
sun's rays.
Heat is transferred from one body to another or to dif-
ferent parts of the same body by conduction, convection,
and radiation.
Conduction :
Page 5
Presented as published in 1913. 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
Flame. — When two substances unite chemically, and both are gases or vapors at the temperature of combustion, the act of union is accompanied by a flame. When one of the substances remains solid at the temperature of combustion, heat and light are given off, but there is no flame. Many substances which are solids or liquids at ordinary temperatures vaporize slowly when at the temperature of burning and hence burn with a flame. The light given by the flame is caused by the glowing, or incandescence, of the solid carbon particles. At a higher temperature the carbon
is quickly and completely burned and gives no light, but burns with a blue flame.
When gas is used as a fuel it is mixed with air before burning, in order that it may be diluted, when there will be a more perfect combustion. A gas used as fuel should burn with a blue flame ; a yellow or a smoky flame indicates that the carbon is not being completely consumed and there is an attendant loss of heat.
NOTE. — Students examine carefully a Bunsen or other gas burner, increasing and decreasing the supply of oxygen by opening and closing the mixer. Note the varying color of the flame and the seeming increase or loss of heat.
Kindling Point. — Every combustible solid must be raised to a certain temperature, or kindling point, before it will unite rapidly enough with oxygen to produce light. This temperature varies with different substances, but is always the same for the same substance. The kindling point of phosphorus is very low. Ordinary parlor matches are tipped with phosphorus, potassium chlorate, and glue. The heat produced by the friction of striking the match is sufficient to raise the phosphorus to its burning point. The heat produced by the burning of the phosphorus raises the wood of the match to its kindling point, and the match ignites.
NOTE. — Student explain the steps in fire building by which hard coal may be raised to its kindling point.
Flash Point. — The temperature to which a fat or oil must be raised before an inflammable vapor is given off is called the flash point. This is a valuable indication of the safety of an oil.
Fuels. — A fuel is a combustible substance usually composed of carbon and hydrogen.
NOTE. — Student prepare a list of fuels —
SOLIDS LIQUIDS GASES
NOTE. — Students inspect specimens of hard and soft woods ; charcoal ; peat ; bituminous, anthracite, and cannel coal ; various fuel oils ; alcohols.
Students write paper on the "Story of Coal."
Students procure the current market price of the various fuels listed above. From the cost of a basket of coal or "bundle of wood," estimate the price paid for a ton of coal and a cord of wood when purchased in small quantities.
Heat. — Heat is molecular motion. Sources of heat :
1. Mechanical energy.
Produced by friction or by collision.
2. Chemical energy.
Produced by combustion or by chemical union of different compounds or elements.
3. Electrical energy.
As produced by an electric toaster, etc., or by the
sun's rays.
Heat is transferred from one body to another or to different parts of the same body by conduction, convection, and radiation.
Conduction :