1889.] on an aitemjJt to apj^If/ to Chemistri/, d'C. 513 



has of forming a hydrate, that is of combining with water ; and the 

 similar attribute of ammonia, resulting in the formation of a caustic 

 alkali, NH^H-O, or XH^OH. 



Having made these indispensable preliminary observations, I may 

 now attack the problem itself and attempt to explain the so-called 

 structure, or rather construction of molecules, that is to say, their 

 constitution and transformations without having recourse to the 

 teaching of " structionists," but on Newton's dynamical principles. 



Of Newton's three laws of motion, only the third can be applied 

 directly to chemical molecules when regarded as systems of atoms 

 among which it must be supposed that there exist common influences 

 or forces, and resulting compounded relative motions. Chemical 

 reactions of every kind are undoubtedly accomplished by changes in 

 these internal movements, respecting the nature of which nothing is 

 known at present, but the existence of which, the mass of evidence 

 collected in modern times, forces us to acknowledge as forming part 

 of the common motion of the universe, and as a fact further 

 established by the circumstance that chemical reactions are always 

 characterised by changes of volume or the relations between the 

 atoms or the molecules. Newton's third law, which is applicable to 

 every system, declares that, " action is always associated with reaction, 

 and is equal to it." The brevity and conciseness of this axiom was, 

 however, qualified by Newton in a more expanded statement, " the 

 action of bodies one upon another are always equal, and in opposite 

 directions." This simple fact constitutes the point of departure for 

 explaining dynamic equilibrium, that is to say, systems of con- 

 servancy. It is capable of satisfying even the dualists, and of 

 explaining, without additional assumptions, the preservation of those 

 chemical types which Dumas, Laurent, and Gerhardt created unit 

 types, and those views of atomic combinations which the structionists 

 express by atomicity or the valency of the elements, and, in connec- 

 tion with them, the various numbers of affinities. In reality if a 

 system of atoms or a molecule be given, then in it, according to the 

 third law of Newton, each portion of atoms acts on. the remaining 

 portion in the same manner, and with the same force as the second 

 set of atoms acts on the first. We infer directly from this considera- 

 tion that both sets of atoms, forming a molecule, are not only equiva- 

 lent with regard to themselves, as they must be according to Dalton's 

 law, but also that they may, if united, replace each other. Let there 

 be a molecule containing atoms ABC, it is clear that, according to 

 Newton's law, the action of A on B C must be equal to the action of 

 B C on A, and if the first action is directed on B C, then the second 

 must be directed on A, and consequently then, where A can exist in 

 dynamic equilibrium, B C may take its place and act in a like manner. 

 In the same way the action of C is equal to the action of A B. In 

 one word every two sets of atoms forming a molecule are equivalent 

 to each other, and may take each other's place in other molecules, or, 

 having the power of balancing each other, the atoms or their comple- 



