252 THE PHENOMENA OF MOTION 



other parts ; and this, in its eftects, is equivalent to 

 an increase of resistance in these other parts. 



The momentum of force of the vitality in the 

 parts which are not cooled is expended, as before, 

 in mechanical motion ; but the whole action of the 

 inspired oxygen is exerted on the cooled part. 



If we imagine an iron cylinder, into which we 

 admit steam under a certain pressure, then if the 

 force with which the particles of the iron cohere be 

 equal to the force which tends to separate them, an 

 equilibrium will result ; that is, the whole effect of 

 the steam will be neutralized by the resistance. 

 But if one of the sides of the cylinder be moveable, 

 a piston-rod, for example, and offer to the pressure 

 of the steam a less resistance than other parts, the 

 whole force will be expended in moving this one 

 side that is, in raising the piston-rod. If we do not 

 introduce fresh steam (fresh force), an equilibrium 

 will soon be established. The piston-rod resists a 

 certain force without moving, but is raised by an in- 

 creased pressure. When this excess of force has 

 been consumed in motion, it cannot be raised 

 higher ; but if new vapour be continually admitted, 

 the rod will continue to move. 



In the cooled part of the body, the living tissues 

 offer a less resistance to the chemical action of the 

 inspired oxygen ; the power of the oxygen to unite 

 with the elements of the tissues is, at this part, ex- 

 alted. When the part has once lost its condition of 

 life, resistance entirely ceases ; and in consequence of 



