EVOLUTION OP HEAT 37 



with 32 grammes of oxygen they form 44 grammes 

 of carbon dioxide. But just as there is a rearrange- 

 ment of the matter so is there a rearrangement of 

 the energy. Clerk Maxwell in his book on " Matter 

 and Motion " says : " The total energy in any 

 material system is a quantity which can neither be 

 increased nor diminished by any action between the 

 parts of the system, although it may be transformed 

 into any of the forms of which energy is susceptible." 

 Thus, in electrical conductivity the potential energy 

 of the molecules becomes kinetic, the molecules are 

 split into ions, and the energy takes a new form, 

 which is positive or negative electricity. Again, 

 during the formation of carbon dioxide from carbon 

 and oxygen, 12 grammes of carbon require 

 32 grammes of oxygen for the formation of 

 44 grammes of C0 2 ; but the potential energy of 

 these amounts of carbon and oxygen is more than 

 is retained by the carbon dioxide, and the excess is 

 transformed into 97,000 calories or units of heat ; 

 therefore C + 2 = C0 2 + 97,000 calories. The heat 

 disengaged during the combination of two or more 

 elements is sometimes called the heat of formation ; 

 and many other instances can be given of the trans- 

 formation of energy into heat during chemical action. 

 A familiar instance in biology is the transformation 

 of organic acids to alkalies or alkaline carbonates. 

 In this process ions are dissociated, e.g. acetates 

 contain the ion acetoxyl C.^fi^O^. During the union 

 of acids and alkalies energy is liberated which is 

 transformed into heat ; from the ionic standpoint 

 the heat arises from the formation of water by the 

 union of H* and OIT ions. The liberated energy is 



