LIVING MATTER AND ITS PRODUCTS 141 



spending changes in other forms of energy as a result of the re- 

 action. The two forms of energy in which such changes of energy 

 can best be expressed are heat energy and mechanical work, or 

 dynamical energy, and it is for this reason that energy exchanges 

 are considered upon a thermo- dynamical basis. 



Energy equilibrium or reaction is determined by the values at any 

 given time of the potential factors of the various forms of energy, 

 by the facilities presented in the system for potential equalisation, 

 and by the manner in which energy is bound or related to par- 

 ticular forms of matter in the system. In so far as any particular 

 form of energy is free to distribute itself throughout the system 

 that particular form of energy tends to equalise its potential all 

 through the system, and hence the energy always passes from a 

 point of higher to a point of lower potential. Thus in any system 

 where redistribution is possible heat always passes from a position 

 of higher to one of lower temperature, electricity from a higher 

 to a lower electrical potential, a fluid or gas from a higher to a 

 lower level of pressure, and so on for every form of energy. In 

 any such change the velocity of equalisation is directly proportional 

 to the difference in potential, and inversely proportional to what 

 is termed the resistance. The resistance, however, means only that 

 the equalisation is opposed by the potential factor of some other 

 form of energy, and that this opposition has to be overcome in 

 effecting the equalisation. If the potential factor of this opposing 

 energy is sufficiently high the equalisation may be entirely stopped, 

 or its speed only may be lessened so that the equalisation takes 

 longer and proceeds with diminished intensity. 



It is impossible for equalisation of potential, or change towards 

 equalisation of potential, of any form of energy to take place without 

 conversion of a portion of the energy so changing potential into 

 other forms, and all physical measurements of change in potential 

 are based upon changes of the energy into other forms. 



In any condition of equilibrium of a system there is a balance 

 between the intensity factors of the various forms of energy capable 

 of interacting with one another, and that balance is dependent 

 upon the facilities provided in the system for interaction between 

 the various forms of energy. Further, in the absence of equilibrium 

 the velocity or intensity of reaction is dependent on the same factors 

 namely, the values of the potential factors and the facilities for 

 interaction. 



