164 NEWTON AND BLACK. 



cohesion, capillary attraction, and gravitation, 

 has never been distinctly understood, or reduced 

 to fundamental laws. 



Had Newton discovered the simple law by 

 which the aether produces the opposite effects of 

 contraction and expansion, he would probably 

 have traced its agency in the phenomena of 

 combustion, solution, vaporization, and all the 

 molecular changes of matter: or had Dr. Black, 

 and his successors, fully comprehended that 

 universal law of caloric by which it attracts pon- 

 derable matter with a force that augments in 

 proportion as bodies are deprived of it, they 

 would have found that it is as capable, under 

 such circumstances, of becoming a powerful bond 

 of cohesion, as it is, under other circumstances, 

 of dissolving their union, and of converting them 

 into elastic fluids. But they have all overlooked 

 the force of attraction, by which this subtile fluid 

 is concentrated around the particles of gravitating 

 matter, and thus rendered latent ; and by which 

 its self-repulsive force is counteracted or des- 

 troyed. 



So imperfectly has Sir Isaac Newton's theory 

 of attraction been understood, that while some 

 of his followers have considered gravitation as a 

 distinct and primary agent, others have regarded 

 it as a fundamental and universal property of 

 matter, by which all bodies tend to a common 

 centre : but I have shewn that Newton referred 



