[ n6 ] [Book II. 



CHAP. IV. 



OF FLUIDITY. 







Caloric equally tkcCewfe of Expanjlcn and Fluidity. Phenomena of 

 Bodies faffing from -a jolid to a fluid State, and the contrary. ./- 

 tenfe Cold of the Southern Hemifphere explained. Dijti nation between 

 Expanjion and Fluidity. Experiments iUmftratwe of the Doflrine of 

 latent Heal, 



IT was intimated that all bodies are capable of con- 

 taining only a limited quantity of caloric, without 

 undergoing an alteration in their external form j the 

 fame caufe which produces expanfion, being increafed 

 to a certain degree, produces a total d involution of the 

 parts of bodies, and reduces them to a fluid ftate ; 

 and a further increafe of the fame power renders them 

 volatile, or caufes them to be carried off in the form 

 of an elaftic fluid, fuch as air or vapour. 



After what has been formerly ftated, it will be no 

 difficult matter to conceive the caufe of all thefe effects 

 to be the fame. The fubtile matter of fire, which 

 appears to be the only fubftartce in nature which is 

 permanently elaftic, or between whofe particles a na- 

 tural re'pulfion exifts, infmuating itfelf between the 

 particles of bodies, deftroys or rather counteracts the 

 natural power of attraction or cohefion, which impels 

 the particles of bodies to approach as nearly in con- 

 tact to each other as poflible. When a body is reduc- 

 ed from a folid to a fluid ftate, a quantity of caloric 

 or fire is abforbed from fome of the furrounding me- 

 dia. The nature of fluids would therefore be, per- 

 haps, not improperly defcribed, by fuppofing them to 

 confift of the very minute particles of the bodies from 



which 



