92 ESSAYS AND OBSERVATIONS 



in it, it will attradl no more. This in 

 particular is the cafe of water fiturated 

 with air, and of air faturated with wa- 

 ter ; for which reafon, there is little or 

 no evaporation in a moid air ; and, for 

 the fame reafon, wind, by removing the 

 moift air, to which dry air fucceeds, is 

 favourable to evaporation. Thirdly, A 

 tnenjiruum diflblves more or lefs in propor- 

 tion to its denfity; becaufe eledtive at- 

 traction muft operate with more or left 

 force, in proportion to the quantity of 

 particles in the menfiruum. This accu- 

 rately holds in air, which, in proportion 

 to its denfity, attradls and difTolves a 

 greater or fmaller quantity of water. 

 Thus, in air-pump experiments, when a 

 part of the air is draw^n out from the re- 

 ceiver, what remains becomes cloudy ; 

 and, upon drawing out more air, the in- 

 fide of the receiver is bedewed with moi- 

 fture ; which, upon re-admitting the air, 

 is again diffolved in it, and the air be- if 

 comes clear as at firft. fourthly. The ac- " 

 tion of every men/lruum is increaled by | 

 heat, and of air in particular, which is ! 



evident 



