nS Phenomena exhibited by Bodies in [Book II. 



confifls of a quantity of pounded ice or fnow with 

 aqua-fortis, or any faline fubftance. The immenfe 

 cold which is fuddenly produced by this procefs, is 

 owing entirely to the fudden liquefaction of the ice, 

 in which cafe all the adjacent bodies mud fupply a 

 quantity of caloric or fire, which is abforbed by the 

 melting ice, and retained by the fluid in a latent ilate, 

 or ftate of combination. Cold is produced by eva- 

 poration, on the fame principle ; the quantity of ele- 

 mentary fire which is attracted by a fluid when pafilng 

 into a rarer (late, and which is required to form at- 

 mofpheres of fire round the particles of the body, fo 

 as to keep them fufpended in the fluid form, is ne- 

 ceffarily fupplied from the furrounding bodies, and 

 muft be attended with a degree of cold. 



The fouthern hemifphere is remarkably colder than 

 that of the north, and even in the midfl of fummer an 

 exceffive degree of cold has been found in the regions 

 which lie near the antarctic circle. To account for 

 thefe phenomena, we muft probably have recourfe to 

 two caufes. As there is a greater extent of water in 

 that hemifphere, the evaporation is confiderably greater 

 than in that of the north ; and as the fouthern ocean 

 abounds with a multitude of immenfe ice iflands, the 

 continual melting of the ice abforbs the matter of fire 

 from all the circumjacent atmofphere ; and in fact we 

 are informed by mariners, that the cold is confiderably 

 increaied by the approach of one of thefe floating 

 mountains of ice. Partly for the fame reafon a thaw 

 is obferved to be much colder than a fettled froft ; 

 though it is alfo to be remembered, that the atmo- 

 fphere is always rather inclined to damp in a thaw, 

 and a damp air is a much more powerful conductor of 

 heat than a dry one. 



On the contrary, when a fluid body pafTes into a. 



foiid 



