208 ESSAYS-anp OBSERVATIONS 
whole of the lune is fucceflively collected 
there under its original form of an in‘ipid 
calcarious earth, called the cream or cruits 
of lime-water. 
WHEN quick-lime itfelf is expofed to 
the open air, it abforbs the particles of 
water and of fixed air which come with- 
in its {phere of attraction, as it meets with 
the firft of thefe in greateft plenty, the 
greateft part of it aflumes the form of fla- 
ked lime; the reft 1s reftored to its origi- 
nal ftate ; and, if it be expofed fora fufh- 
cient length of time, the whole of it is gra- 
dually faturated with air, to which the 
water as gradually yields its place. 
We havealready fhewn by experiment, 
that mignefia alba is a compound of a 
peculiar earth and fixed air. When this 
fubftance is mixed with lime-water, the 
lime fhews a ftronger attraction for fixed 
air than that of the earth of meguefia ; the 
air leaves -this powder to join itfelf to 
the lime. And as neither the lime when 
faturated with air, nor the maguefia when 
deprived of it, are foluble in water, 
the lime water becomes perfectly pure and 
infipid, 
