1 30 fPby Fluids loll in Vacuo with [Book II* 



at 122 below their ordinary boiling point, it is natu- 

 ral that ether, which boils in the open air at about the 

 heat of the human blood, (hould boil in vacuo at 24 

 below o, a degree of cold fufficient to freeze any wa- 

 ter that might happen to be in contact with the vefTel 

 which contains the ether. 



As the weight of the atmofphere varies fome degrees 

 at different times, it is evident, from thefe remarks, 

 that the boiling point of fluids will alfo occafionally 

 vary. Boerhaave fuppofes, that, according to the 

 "changes of the atmofphere, as marked by the barome- 

 ter, the heat of boiling water may vary occafionally 

 eight or nine degrees * ; and we find the opinion cofl- 

 rirmed by the accurate experiments of M. de Luc and 

 Sir George Shuckburg, in the courfe of which the 

 boiling point was fometimes lower than 205, and 

 fometimes higher than 2 1 3 f. 



* Boerhaave Chem. quoted by Watfon, Chem, Efl*. vol.iii. p. 157. 

 t This will be better underftood by exhibiting Mr. Cavallo's 

 table of the refult of each experiment. 



Water boiling hot cools in fix hours in th ordinary heat of the 

 actmcfphere. 



Some 



