116 MODERN SCIENCE READER 



of a combination of the metal calcium with the gas oxygen, 

 and the energy of union is so great that the metal calcium, 

 though one of the most common of nature's so-called ele- 

 ments, is hardly known in nature except as an oxide or a 

 carbonate. 



Aluminium is a metal that unites so firmly with oxygen 

 that it will usurp the place of iron in a mass of burned 

 iron, and convert a mass of mill scale into pure iron by 

 itself becoming an oxide. Hence the thermic process. The 

 fuels that are commonly regarded as fuels are wood and 

 coal and mineral oils. These are found free in nature, and 

 are easily burned and give out considerable heat. Ages of 

 experience have taught us that air is necessary to combus- 

 tion. The fire of wood burns the better when the wind 

 blows upon it. The wind we can feel, if we cannot see it. 

 The effect is to blow away the C0 2 and leave the fuel freely 

 exposed to fresh supplies of oxygen. 



Carbon gas is ideal only. Carbon exists, as gas, in the 

 electric arc at 3,600 C. When carbon is burned to 

 monoxide, CO, there are set free 4,415 B.t.u. per pound. 

 When this monoxide is burned to dioxide a further heat of 

 10,232 B.t.u. is set free. Why the difference ? Physicists 

 say that the first oxidation also generates at least 10,232 

 B.t.u. or 5,817 units more than is thermometrically discov- 

 erable. They say that the 5,817 units have become latent 

 because the carbon which was solid is now gaseous in the 

 CO. Therefore, the total heat of combustion of carbon 

 gas, if carbon could be taken in its gaseous form, is 10,232 

 X 2=20,464 B.t.u. per pound. 



Now, in CO 2 there are 12 parts of C. and 32 parts of 0, or 

 C : : : 3 : 8. 



Then 20,4 64 X%= 7, 674 



B.t.u. produced by the combustion of one pound of oxygen. 



Now, for combustion with hydrogen : One pound of this 

 gas gives 62,100 B.t.u. The ratio of the two elements 

 H 2 is 1 : 8. 



Now, 62,100xys=7J63 



