province which is termed either 'theoretical' or 'physical' chemistry, or, 

 better still, flo'ni'n-nl m^-hnnics. As this province of chemistry re- 

 quires a knowledge not only of the various homogeneous substances 

 which have yet been obtained and of the chemical transformations which 

 they undergo, but also of the phenomena (of heat and other kinds) by 

 which these transformations are accompanied, it is only possible to 

 nter on the study of chemical mechanics after an acquaintance with 

 the fundamental chemical conceptions and substances which form the 

 subject of this book. 31 



r>1 I consider that in an elementary textbook of chemistry, like the present, it is only 

 possible and advisable to mention, in reference to chemical mechanics, a few general 

 ideas and some particular examples referring more especially to gases, whose mechanical 

 theory must be regarded as the most complete. The molecular mechanics of liquids and 

 solids is as yet in embryo, and contains much that is disputable; for this reason, 

 chemical mechanics has made less progress in relation to these substances. It may not 

 be superfluous to here remark, with respect to the conception of chemical affinity, that up 

 to the present time gravity, electricity, and heat have been respectively applied to its 

 elucidation. Efforts have also been made to introduce the luminiferous ether into 

 theoretical chemistry, and should that connection between the phenomena of light and 

 electricity which was established by Maxwell be worked out more in detail, doubtless 

 these efforts to elucidate all or a great deal by the aid of luminiferous ether will yet again 

 appear in theoretical chemistry. An independent chemical mechanics of the material 

 particles of matter, and of their internal (atomic) changes, would, in my opinion, arise a - 

 the result of these efforts. Just as the progress made in chemistry in the time of 

 Lavoisier was reflected over all natural science, so there is reason to think that an in- 

 dependent chemical mechanics would shed a new light on all molecular mechanics, which 

 must be considered as the fundamental problem of the exact sciences in our times. Two 

 hundred years ago Newton laid the foundation of a truly scientific theoretical mechanics 

 of extemal visible movement, and erected the edifice of celestial mechanics on this 

 foundation. One hundred years ago Lavoisier arrived at the first fundamental law of the 

 internal mechanics of invisible particles of matter. This subject is far from having been 

 developed into a harmonious whole, because it is much more difficult, and, although many 

 details have been completely investigated, it does not possess any starting points. 

 Newton was possible only after Copernicus and Kepler, who had discovered the exte- 

 rior empirical simplicity of celestial phenomena. Lavoisier and Dalton may, in respect 

 to the chemical mechanics of the molecular world, be compared to Copernicus and 

 Kepler. But a Newton has not yet appeared in the molecular world ; when he does, I 

 think that he will find the fundamental laws of the mechanics of the invisible movements 

 of matter more easily and more quickly in the chemical structure of matter than in 

 physical phenomena (of electricity, heat, and light), for these latter are accomplished by 

 already-disposed particles of matter, whilst it is now clear that the problem of chemical 

 mechanics mainly lies in the apprehension of those movements which are invisibly ac- 

 complished by the smallest atoms of matter. The general laws of mechanics, established 

 by Newton, will probably serve as starting points for molecular mechanics, but the 

 independence of its range becomes more evident when chemical molecules are com- 

 pared with the celestial systems, such as the solar system. Chemical atoms may be 

 regarded as separate members of such systems (as, for instance, the sun, planets, comets, 

 and other heavenly bodies), whilst the ether of light may be likened to the cosmic dust 

 which without doubt is distributed throughout space. The present condition of molecular 

 mechanics is, to a certain extent, copied from celestial mechanics, but there is nothing to 

 prove the entire similarity of both worlds, although it appears to the mind that, starting 

 from the primary elements of the unity of creation, such a representation is the most 



likelv. 



