So GENERAL SCIENCE 



when they make starch. Since oxygen in large amounts 

 is necessary for burning, fires will not burn well when 

 they do not get enough air to supply the oxygen. In 

 most gas lamps the gas is mixed with air before it flows 

 to the part where it burns. This insures more perfect 

 oxidation of the gas and hence a better light. A current 

 of air is allowed to flow into the fire of a furnace to supply 

 oxygen. The gas that comes from a fire or gas lamp 

 has a large per cent of carbon dioxide. 



36. Kindling Point and Spontaneous Combustion. - 

 The kindling point of a substance is that temperature 

 at which the substance will begin to burn in a flame. 

 Various substances have a different kindling point, and 

 the smaller the amount of the substance, the easier it is 

 to raise its temperature to that point. For this reason 

 when we want to start a wood or coal fire we place shav- 

 ings at the bottom and on these fine kindling wood and 

 then heavier wood, and finally on top of all this material 

 we place larger pieces of wood or coal. The burning 

 match will raise the temperature of the shavings to the 

 burning or kindling point, and they in turn will heat /the 

 kindling wood, and so on up to the kindling temperature 

 of the largest wood or coal. When wood or coal is heated 

 to the kindling point a gas escapes, and the burning of 

 this gas is what makes the flame. Sometimes hay in a 

 barn or old rags and paper stored in sheds or closets, 

 become so hot that the kindling temperature is reached, 

 and the whole building containing the material will burst 

 into flame; this is called spontaneous combustion. 



The ancient method of raising wood to the kindling 

 temperature was by friction, that is, by rubbing two 

 sticks together till they caught fire. The American 

 Indians used this method. Then came into use the 



