On Cohesion. 83 



The particles of bodies being individually too minute to come 

 directly under the observation of our senses, we can only arrive 

 at a knowledge of their nature and properties through the me- 

 dium of the nature and properties of their aggregates. 



The general admission of the two following positions, drawn 

 from the known properties of bodies and our ideas of the wisdom 

 and goodness of the great Author of Nature, may claim for them 

 the rank of axioms*. 1st, That all matter is ultimately composed 

 of infinitely miniite particles. 2dly, That these ultimate par- 

 ticles are perfectly solid, impenetrable, and consequently im- 

 mutable bodies. To these may l)e added a third; viz. That the 

 particles of which all bodies, whether simple or compound, are 

 directly composed, are homogeneous. For with respect to simple 

 l)odies this cannot be for a moment doubted; and of compounds 

 we can form no other idea than that they are either a mixture of 

 particles, or that by a certain action the diiiering particles com- 

 bine, and thus the whole are rendered similar. That the mere 

 admixture of particles is insufficient to produce a true chemical 

 compound is universally allowed ; we must therefore conclude, 

 that the particles of which all bodies are directly formed are ho- 

 mogeneous. Now a chemical compound is produced by pre- 

 senting the particles of different bodies to one another; and the 

 particles of a chemical compound being homogeneous, it follows 

 that the particles of the component bodies must have undergone 

 a change, by which their individuality has been destroyed. The 

 particles of which bodies are dikectja' composed, must there- 

 fore be penetrable and changeable properties, which according 

 to our axiom cannot belong to the ultimate particles of matter. 

 Hence it may be fairly inferred, that the particles of which bodies 

 are directly formed, differ essentially from the ultimate particles of 

 matter; and that bodies must be composed of at least two kinds 

 of particles, which may be called primary or direct, and ultimate 

 particles : the primary particles, it has been shown, are homoge- 

 neous; the ultimate particles arc similar or dissimilar, according 

 as they compose simple or compound bodies. Whether there be 

 more than two descriptions of particles or not, does not appear f : — 

 the primary particles may be composed of other secondary ones, 

 these of others, and so on ad ivjinilum, where perhaps are the 

 ultimate particles of matter. 



The attraction called gravity is an universal property of mat- 

 ter : it is found in similar bodies in proportion to their masses or 

 quantities of particles. It may therefore be inferred that this at- 

 traction exists in the particles of bodies as well as in the bodies 



• In support of these uxionis may be adduced the opinions of Sir I. New- 

 ton, Haxter, )kc. 



f On this subject I shall communicate something in tlic next Number of 

 this MuL'azine. F 2 tlicmselvcs 



