[184] 
' xliffufed as to become invifible. Quantities of dull 
are thus carried up in dry feafons. Showers wafh it 
from the air and bring it down again. For water 
attradling it dronger, it quits the air and adheres to 
the water. 
Air fuffering continual changes in the degrees of 
its heat, from various caufes and circumftances, and 
oonfequently changes in its fpecific gravity, muft 
therefore be in continual motion. 
-A fmall quantity of fire mixed with water (or de- 
gree of heat therein) fo weakens the cohefion of its 
particles, that thofe on the fiirface eafily quit it, and 
adhere to the particles of air. 
, A greater degree of heat is required to break the 
cohefion between water and air. 
Air moderately heated will fupport a greater quan- 
tity of water invifibly than cold air j for its particles 
being by heat repelled to a greater difiance from 
each other, thereby more eafily keep the particles of 
water, that are annexed to them, from running into 
cohefions that would obfirudt, refradt, or refledt the 
light. 
Hence, when we breathe in warm air, though the 
fiime quantity of moifiure may be taken up from 
the lungs as when we breathe in cold air, yet that 
moifiure is not fo vifible. 
Water being extremely heated, /. e. to the degree 
of boiling, its particles, in quitting it, fo repel each 
other, as to take up vafily more fpace than before, 
and by that repellency fupport themfelves, expelling 
the air from the fpace they occupy. That degree of 
heat being lefiTened, they again mutually attradf, and 
having no air-particles mixed, to adhere to, by 
2 which 
