E 101 ] 
fait, when dilToIved in a great quantity of water, does 
not make any precipitate on the addition of fixed 
alkali. 
There is great reafon to fuppofe that the earth preci- 
pitated on mixing the Rathbone-place water and lime- 
water, was very nearly faturated with fixed air, i. e. 
that it contained very near as much fixed air, as is na- 
turally contained in the fame quantity of calcarious earth. 
If fo, 30 ounces of Rathbone-place water contain as 
much .fixed air as 39 grains of calcarious earth ; whereas 
the unneutralized earth, in that quantity of water, is 
only 164. grains ; fo that Rathbone place water con- 
tains near 2 4 times as much fixed air as is fufficient 
to faturate the unneutralized earth in it. 
It feems likely from hence, that the fufpenfion of 
the earth in the Rathbone-place water, is owing 
merely to its being united to more than its natural 
proportion of fixed air ; as we have fihewn that this 
earth is actually united to more than double its na- 
tural proportion of fixed air, and alfo that it is im- 
mediately precipitated, either by driving off the fuper- 
fiiuous fixed air by heat, or abforbing it by the ad- 
dition of a proper quantity of lime water. 
Calcareous earths, in their natural ftate, i. e. fatu- 
rated with fixed air, are totally infoluble in water ; 
but the fame earths, entirely deprived of their fixed 
air, i. e. converted into lime, are in fome meafure 
foluble in it ; for lime-water is nothing more than a 
folution of a fmall quantity of lime in water. It is 
very remarkable, therefore, that calcareous earths 
fihould alfo be rendered foluble in water, by fur- 
nifhing them with more than their natural propor- 
tion of fixed air, i. e. that they fhould be rendered 
foluble, both by depriving them of their fixed air, 
