16 Mr. J. Croll on What determines Molecular Motion ? — 



are the same; only they act differently. But if this be what is 

 meant, then assuredly every force in nature is either chemical or 

 physical. But this would be using the terms chemical and 

 physical energies in a peculiar and unusual sense. 



^¥e are accustomed to name forces and energies according to 

 their mode of operation. Oxygen and hydrogen unite under 

 the force of their affinities ; and we designate the energy of the 

 combining substances " chemical energy.'''' After combination 

 the energy assumes another form ; and we call it " heat.''^ The 

 heat is applied to the thermo-electric pile and becomes trans- 

 formed ; and we call the energy under the new form by the name 

 " electricity ^' or ^^ electric current. '"' The electricity is applied 

 to the electromagnetic machine; and the energy assumes another 

 form, to which the name '^ magnetism " is applied. The mag- 

 netism propels a machine and performs mechanical work; and 

 we then call the energy " m.echanical energy.^'' These various 

 names are applied to the various modes of operation of the self- 

 same energy. Chemical energy, for example, in the case under 

 consideration, differs from heat only in the mode of its operation. 



We have also been accustomed to group heat, light, electri- 

 city, magnetism, gravity, cohesion, kc, under one class, to which 

 we apply the general term physical, or physical energy, in contra- 

 distinction to chemical energy. We thus distinguish chemical 

 energy from all the other forms, because we conceive it to be 

 concerned with the combinations and motions of the atoms or 

 elements of substances, whereas the other class deals with the 

 molecules and masses of matter. 



Now when the advocates of the physical theory of life affirm 

 that every energy in organic nature is either chemical or phy- 

 sical, they certainly do not mean to include under the term 

 physical every form of energy which does not, like chemistry^ 

 deal with the elementary substances ; for if this were their 

 meaning, it would be simply a truism to say that all energy is 

 either chemical or physical. By physical energy they un- 

 doubtedly mean the ordmary and known forms of energy mani- 

 fested in the inorganic world, to which we give the various spe- 

 cific names of attraction, repulsion, light, heat, electricity, 

 magnetism, and so forth. But here we now approach the real 

 question at issue, viz. are these forms of energy along with che- 

 mical energy sufficient to account for the phenomena of life and 

 organic nature ? 



Chemistry and physics are insufficient, because they do not 

 account for the objective idea in nature. 



Whatever maybe one^s opinions regarding the doctrine of Final 

 Causes and the evidence of design in nature, all must admit the 

 existence of the objective idea in nature. We see everywhere 



