1889.] on an attempt to apply to Chemistry, dc. 507 



of their metals, and have derived, for the conviction of the incredulous, 

 a mixture of two hygroscopic though solid salts— nitrate of soda and 

 acetate of j^otash ? 



In these invisible and apparently chaotic movements, reaching 

 from the stars to the minutest atoms, there reigns, however, a 

 harmonious order which is commonly mistaken for complete rest, but 

 which is really a consequence of the conservation of that dynamic 

 equilibrium which was first discerned by the genius of Newton, and 

 which has been traced by his successors in the detailed analysis of 

 the particular consequences of the great generalisation, namely, 

 relative immovability in the midst of universal and active movement. 



But the unseen world of chemical changes is closely analogous to 

 the visible world of the heavenly bodies, since our atoms form distinct 

 portions of an invisible world, as planets, satellites, and comets form 

 distinct portions of the astronomer's universe ; our atoms may there- 

 fore be compared to the solar systems, or to the systems of double or 

 of single stars, for exaniijle, ammonia (NH^) may be represented in 

 the sim2)lest manner by supposing the sun nitrogen surrounded by 

 its planets of hydrogen ; and common salt (NaCl) may be looked 

 upon as a double star formed of nitrogen and chlorine. Besides, now 

 that the indestructibility of the elements has been acknowledged, 

 chemical changes cannot otherwise be explained than as changes of 

 motion, and the production by chemical reactions of galvanic currents, 

 of light, of heat, of pressure, or of steam power, demonstrate visibly 

 that the processes of chemical reaction are inevitably connected with 

 enormous though unseen displacements, originating in the movements 

 of atoms in molecules. Astronomers and natural j^hilosophers, in 

 studying the visible motions of the heavenly bodies and of matter on 

 the earth, have understood and have estimated the value of this store 

 of energy. But the chemist has had to pursue a contrary course. 

 Observing in the physical and mechanical phenomena which accom- 

 pany chemical reactions the quantity of energy manifested by the 

 atoms and molecules, he is constrained to acknowledge that within 

 the molecules there exist atoms in motion, endowed wdth an energy 

 which, like matter itself, is neither being created nor is capable of 

 being destroyed. Therefore, in chemistry, we must seek dynamic 

 equilibrium not only between the molecules but also in their midst 

 among their component atoms. Many conditions of such equilibrium 

 have been determined, but much remains to be done, and it is not 

 uncommon, even in these days, to find that some chemists forget that 

 there is the possibility of motion in the interior of molecules, and 

 therefore re]3resent them as being in a condition of death-like 

 inactivity. 



Chemical combinations take place with so much ease and rapidity ; 

 possess so many special characteristics, and are so numerous, that 

 their simplicity and order was for a long time hid from investigators. 

 Sympathy, relationship, all the caprices or all the fancifulness of 

 human intercourse, seemed to have found complete analogies, in 



Vol. XII. (No. 83.) 2 m 



