170 CAUSE OF SOLIDITY. 



It still remains to prove that the cohesion of 

 metals, rocks, and all other solid bodies, is de- 

 termined by the various degrees of force with 

 which they attract caloric ; and that it is resolv- 

 able into the same cause which produces the 

 contraction and chemical combination of gases, 

 or reduces them to the form of liquids. If it can 

 be established as a general law, that the particles 

 of all bodies are held together, with forces which 

 vary according to the different degrees of their 

 affinity for caloric, and that this affinity varies 

 with every change in the relative proportions of 

 caloric and ponderable matter, the problem of 

 attractions will be greatly simplified ; for it will 

 be evident that cohesion is not the result of 

 pressure, as conjectured by Newton, but that 

 contraction and expansion, density and lightness, 

 solidity and fluidity, are modified effects of one 

 and the same agent ; in fine, that all the ope- 

 rations of nature depend on the relations of sethe- 

 real and ponderable matter. 



A thorough comprehension of the law by which 

 caloric is chained down in a state of intimate 

 combination with the ponderable matter of the 

 earth, and thus prevented from expanding 

 throughout the universe, would banish from the 

 science of Physics all those vague and absurd 

 speculations, which have been founded on hypo- 

 thetical data, such as innate forces, immaterial 

 properties, occult qualities, inertia of atoms, &c. 



