OMcl the Molecular Energy of Matter. 85 



work upon other matter, we should at once remove this 

 inconsistency. 



Our proposition would then be that two portions of matter 

 animated by vast internal energies which are similar in all 

 respects to the energies of animals, except that they are not 

 accompanied by consciousness, have by ^drtue of this internal 

 energy the power of doing work. 



I desire in this paper to inquire how far we should be 

 justified in thus seeking in the known molecular energy of 

 matter the attractive power which this matter certainly 

 possesses. 



If there be two bodies at a certain distance from one 

 another, each is found after a certain time to be possessed of 

 kinetic energy, which was not previously in existence; and we 

 have to inquire from what source this energy has been derived. 



In accordance with the principle of the conservation of 

 energy, the reply must be that it has sprung from some an- 

 tecedent energy; for if the sum total of energy in the universe 

 be constant then energy cannot be created, and cannot be 

 produced from something which is not energy. 



Now let us ask — What is the pre-existent energy from 

 which the energy of these attracting bodies has been 

 derived ? 



We must carefully avoid being misled by the use of such 

 a term as " Potential Energy ;" for in referring the energy 

 whose origin we seek to what is called potential energy, we 

 should at once beg the whole question. When Professor 

 Rankine invented this term, he never intended that it should 

 be used to represent any real form of energy. It is an 

 analytical artifice of great use, but merely representing the 

 potentiality as distinguished from the actual existence of 

 energy. It is a condensed statement of the fact that if a 

 body be left to itself it will after a certain time have 

 acquired a certain amount of energy. But the question 

 we propose is still untouched — From what source has this 

 derived energy been obtained ? 



We have to decide in what direction we may^ with most 

 hope of success, seek this unknown source. Is it external 

 to the attracting bodies, or is it internal ? In other words, 

 when two portions of matter in space begin to move towards 

 one another, is this motion due to external energies driving 

 them together, or to the internal energies of matter itself 

 tending to draiu the two portions together ? 



