1889.] on an attempt to apply to Chemistry, dc. 509 



most important change has taken place in the views, and consequently 

 in the researches of chemists. They have sought everywhere, and 

 have always found systems of conservation or dynamic equilibrium 

 substantially similar to those which natural philosophers have long 

 since discovered in the visible world, and in virtue of which the 

 position of the heavenly bodies in the universe is determined. There 

 where one-sided affinities only were at first detected, not only secondary 

 or lateral ones have been found, but even those w^hich are diametri- 

 cally opj)osite, yet among these, dynamical equilibrium establishes 

 itself not by excluding one or other of the forces, but regulating them 

 all. So the chemist finds in the flame of the blast furnace, in the 

 formation of every salt, and, with especial clearness, in double salts, 

 and in the crystallisation of solutions, not a fight ending in the 

 victory of one side, as used to be supposed, but the conjunction of 

 forces ; the peace of dynamic equilibrium resulting from the action of 

 many forces and affinities. Carbonaceous matters, for example, burn 

 at the expense of the oxygen of the air, yielding a quantity of heat 

 and forming products of combustion, in which it was thought that the 

 affinities of the oxygen with the combustible elements were satisfied. 

 But it appeared that the heat of combustion was competent to de- 

 compose these products, to dissociate the oxygen from the combustible 

 elements, and therefore, to explain combustion fully, it is necessary to 

 take into account the equilibrium between opposite reactions, between 

 those which evolve, and those which absorb heat. 



In the same way, in the case of the solution of common salt in 

 water, it is necessary to take into account, on the one hand, the 

 formation of compound particles generated by the combination of salt 

 with water, and on the other the disintegration or scattering of the 

 new particles formed, as well as of those originally contained. At 

 l^resent we find two currents of thought, apj^arently antagonistic to 

 each other, dominating the study of solutions : according to the one, 

 solution seems a mere act of building up or association ; according to 

 the other, it is only dissociation or disintegration. The truth lies, 

 evidently, between these views ; it lies, as I have endeavoured to 

 prove by my investigations into aqueous solutions, in the dynamic 

 equilibrium of particles tending to combine and also to fall asunder. 

 The large majority of chemical reactions which appeared to act 

 victoriously along one line have been proved capable of acting as 

 victoriously even along an exactly opposite line. Elements which 

 utterly decline to combine directly may often be formed into com- 

 paratively stable compounds by indirect means, as for example in the 

 case of chlorine and carbon ; and consequently the symjDathies and 

 antipathies, which it was thought to transfer from human relations to 

 those of atoms, should be laid aside until the mechanism of chemical 

 relations is explained. Let us remember, however, that chlorine, 

 which does not form with carbon the chloride of carbon, is strongly 

 absorbed, or, as it w^ere, dissolved by carbon, which leads us to 

 suspect incipient chemical action even in an external and purely 



2 M 2 



