14 THE ORIGIN AND EVOLUTION OF LIFE 



being exemplified mechanically by the bent spring, chemi- 

 cally by gunpowder, and electrically by a Leyden jar — and 

 kinetic energy, the active energy of motion and of heat. 



While all active mechanical energy or work may be con- 

 verted into an equivalent amount of heat, the opposite process 

 of turning heat into work involves more or less loss, dissipa- 

 tion, or degradation of energy. This is known as the second 

 law of thermodynamics and is the outgrowth of a principle dis- 

 covered by Sadi Carnot (1824), and developed by Kelvin (1852, 

 1853). The far-reaching conception of cyclic processes in en- 

 ergy enunciated in Kelvin's principle of the dissipation of 

 available energy puts a diminishing limit upon the amount of 

 heat energy available for mechanical purposes. The available 

 kinetic energy of motion and of heat which we can turn into 

 work or mechanical effect is possessed by any system of two 

 or more bodies in virtue of the relative rates of motion of their 

 parts, velocity being essentially relative. 



These two great dynamical principles that the energy of 

 motion can be converted into an equivalent amount of heat, 

 and that a certain amount of heat can be converted into a 

 more limited amount of power were discovered through obser- 

 vations on the motions of larger masses of matter, but they 

 are believed to apply equally to such motions as are involved 

 in the smallest electrically charged atoms (ions) of the chem- 

 ical elements and the particles flying off in radiant energy as 

 phosphorescence. Such movements of infinitesimal particles 

 underlie all the physicochemical laws of action and reaction 

 which have been observed to occur within living things. In 

 all physicochemical processes within and without the organism 

 by which energy is captured, stored, transformed, or released 

 the actions and reactions are equal, as expressed in Newton's 

 third law. 



