ELEMENTARY PRINCIPLES. 39 



leaves the mind in a state of uncertainty and bewilder- 

 ment. 



Adapting the views of Dumas, with some modifica- 

 tions,* it will be found more satisfactory to regard the 

 ultimate atoms of matter as points beyond the reach of 

 our examination ; which, according to a law, determined 

 by the influences of the so-called imponderable forces, 

 unite to form molecules. Again, these molecules com- 

 bine to form the particles of the mass which we may 

 regard as the limit of mechanical division. The particles 

 of solid bodies are solid, those of fluids fluid, and those of 

 gaseous bodies are themselves aeriform ; but it does not 

 follow that the molecules of any body should be neces- 



-:- '-Two very different hypotheses have been formed to ex- 

 plain the nature of matter, or the mode of its formation ; the 

 one known as the atomic theory, the other, the dynamic. The 

 founder of the former and earlier was Leucippus: he consi- 

 dered the basis of all bodies to be extremely fine particles, 

 differing in form and nature, which he supposed to be dispersed 

 through space, and to which his follower Epicurus first gave 

 the name of atoms. To these atoms he attributed a rectilinear 

 motion, in consequence of which such as are homogeneous 

 united, whilst the lighter were dispersed through space. The 

 author of the second hypothesis was the famous Kant He. 

 imagined all matter existed, or was originated, by two antagonist 

 and mutually counteracting principles, which he called attraction 

 and repulsion, all the predicates of which he referred to motion. 

 Most modern philosophers, and foremost amongst them Ampere 

 and Poisson, have adopted an hypothesis combining the features 

 of both the preceding. They regarded the atoms as data, deriving 

 their origin from the Deity as the first cause, and consider their 

 innate attractive and repulsive force as a necessary condition to 

 their combination in bodies. The main features of this hypothesis 

 are borrowed from Aristotle, inasmuch as he supposed the basis 

 of all bodies to be the four elements known to the ancients, the 

 particles of which, endued with certain powers, constituted 

 bodies. According to Ampere, all bodies consist of equal particles, 

 and they again of molecules that, up to a certain distance, 

 attract each other. Their distance from each other he supposed 

 to be regulated by the intensity of the attractive and repulsive 

 forces, the latter of which preponderates." PeschePs Elements of 

 Physics; translated by E. West, 1845. 



