[ 287 ] 



vapours which had paffed the limits of faturation, and therefore 

 have, in feme degree, coalefced ; but their farther coalefcence into 

 rain is ow^ing to eledrical agency, as the Dodor himfelf well ex- 

 plains in the fucceeding pages. ■ 



The evaporation of water expofed to the air is encreafed or di- 

 xninifhed by various circumflances, fome relative to the water and 

 fome relative to the air. Thofe relative to the water are, i''. its 

 temperature; 2^. itsfurface; and, 3'^. its purity. 



And i*^. di5 to temperature. It appears from Lambert's experi- 

 ments made, in a room in which there was a ftove whofeheat 

 could be regulated, that evaporation proceeds in a different ratio 

 from our artificial degrees. The refults are exhibited in the fol- 

 lowing table : 



The degrees of heat were taken by Lambert on Reaumur's fpirit 

 thermometer, and the evaporation eftimated by lines of the Paris 



N n 2 inch. 



