DEATH AND RESURRECTION. 97 



nor the molecules within the visible 

 body, are packed closely together. 

 They are separated by comparatively 

 great spaces. But if these building 

 stones are separated from each other 

 we might expect that they would be- 

 have like the grains in a sand heap. 



How can material bodies then be 

 solid, hard, tough, etc.? The reason is 

 that the spacing in question is regu- 

 lated by other forces of essentially 

 different kind. We have attracting as 

 well as repelling forces, such as tend 

 to increase as well as to reduce the 

 distances between the particles. 



We shall first consider the attract- 

 ing forces, and these are called co- 

 hesion and adhesion when exerted be- 

 tween molecules. The mutual attrac- 

 tion between the atoms within the 

 molecules has been named affinity or 

 chemical energy. 



Turning again to the form of energy 

 acting in the opposite direction, we 

 find just the force we are in search 



