ELECTRONS AND ATOMS 35 



in pressure ; (b) magnetic bodies at rest near 

 a magnet ; (c) a coiled spring ; (d) chemical 

 energy due to juxtaposition of molecules or 

 atoms, such as is typically seen in a high 

 explosive, but all chemical substances possess 

 such potential energy ; (d) the heat which 

 disappears without change of temperature 

 when a solid turns into liquid, or a liquid 

 into gas, as in the formation of water from 

 ice or steam from water, this is called " latent 

 heat," but is really not heat at all ; (e) surface 

 tension, such as is seen in a soap-bubble, or 

 at any interface at rest between two dissimilar 

 forms of matter. 



These two lists are not exhaustive but are 

 intended to show two things, first, the large 

 number of discrete forms of energy which 

 exist, each with a set of natural phenomena 

 of its own, and, secondly, how completely 

 different the first set of forms of energy 

 termed kinetic are from the members of the 

 second or potential type. The first are forms 

 of activity, the second, forms of passivity, 

 but a definite measured amount may pass 

 from any one form to another, and in the 

 exchange there is never any gain or loss in 

 amount, but always an exact balance. One 

 passive form cannot pass into another passive 

 form without intermediately passing through 



