go (M) 



tions to consider for a moment the potential energies or 

 attractions, we find, also, an intimate correlation. Since 

 all energy not active in motion is potential in attraction, 

 it follows that in the attractions we have energy stored 

 up for subsequent use. The sun is thus storing up 

 energy : every minute it raises 2,000,000,000 tons of 

 water to the mean hight of the clouds, 3^2 miles ; and 

 the actual energy set free when this water falls is equal 

 to 2,757,000,000,000 horse powers. Z 9 So when the oxy- 

 gen and the zinc of the ore are separated in the furnace, 

 the actual energy of heat becomes the potential energy of 

 chemical attraction, which again becomes actual in the 

 form of electricity when the zinc is dissolved in an acid. 

 We see, then, that not only may any form of force or 

 actual energy be stored up as any form of attraction or 

 potential energy, but that the latter, from whatsoever 

 source derived, may appear as heat, light, electricity, or 

 mechanical motion. 



Having now established the fact of correlation for 

 the physical forces, we have next to inquire what are 

 the evidences of the correlation of the vital forces with 

 them. But in the first place it must be remarked that 

 life is not a simple term like heat or electricity ; it is 

 a complex term, and includes all those phenomena 

 which a living body exhibits. In this discussion, there- 

 fore, we shall use the term vital force to express only 

 the actual energy of the body, however manifested. As 

 to the attractions or the potential energy of the organ- 

 ism, nothing is more fully settled in science than the 

 fact that these are precisely the same within the body 

 as without it. Every particle of matter within the body 

 obeys implicitly the laws of the chemical and physical 



