8 DIFFUSION AND OSMOTIC PRESSURE 



together, until cohesion becomes so strong, and hence the 

 friction of particle upon particle so great, that the free 

 movement upon each other just described comes practically 

 to an end. The body is now a solid and will retain its form 

 without surrounding walls. The particles are still in violent 

 vibration, however. It should be stated here that the ideal 

 gas, liquid, or solid does not exist; the hardest substances 

 show some tendency to flow like liquids, and the most fluid 

 substances exhibit some friction of their component particles 

 upon one another. 



