188 THEORY OF COHESION. 



In fine, the more profoundly we scrutinize the 

 operations of nature, the more evident it becomes, 

 that all the modifications of force by which the 

 particles of bodies are united, depend on the 

 various degrees of their attraction for a self-re- 

 pulsive aether ; and that they cohere with a force 

 proportional to their affinity for caloric. It is 

 therefore ridiculous to maintain, that an agent 

 which repels its own particles, cannot hold toge- 

 ther the particles of other bodies. 



Theory of Conduction and Radiation. 



The most general and well established fact 

 connected with conduction is, that all the lightest 

 bodies in nature are bad conductors of caloric 

 and electricity ; such as furs, eider down, silks, 

 woollens, cottons, resins, lac, bitumins, phos- 

 phorus, dry w r ood, &c. among solids ; and aether, 

 alcohol, oils, and water, among liquids; while 

 gases are still worse conductors whereas, the 

 densest known bodies are good conductors, such 

 as gold, silver, platina, mercury, copper, &c. 

 Next to the pure metals in conducting power, 

 are rocks, gems, flint glass, porcelain, and the 

 denser liquids, as solutions of the acids and 

 alkalies. Owing to their extreme fusibility, it is 

 difficult to determine the conducting power of 

 potassium and sodium; but it is certain that 



