[ 100 ] 
Experiment IV. 
The following experiment fhews that the fixed air 
was not generated during the boiling, but was con- 
tained in the water before. Into 30 ounces of 
Rathbone-place water was poured fome lime-water, 
which immediately made a precipitate. More lime- 
water was added, till it ceafed to make any farther 
precipitate. It required 2cJL ounces. The precipi- 
tated earth being dried weighed 39 grains. 
The unneutralized earth contained in 30 ounces of 
Rathbone-place water is 16 1- grains, and the earth 
contained in 201. ounces of lime-water (as was found 
by precipitating the earth by volatile fal ammoniac) is 
2 1 grains. Therefore the earth precipitated from the 
mixture of Rathbone-place water, and lime-water, is 
about equal to the fum of the weights, of the earth 
contained in the lime-water, and of the unneutralized 
earth in the Rathbone-place water ; and consequently 
all the un neutralized earth feems to be precipitated 
from Rathbone-place water by the addition of a proper 
quantity of lime-water. But a more convincing 
proof that this is the cafe, is that the clear liquor, 
after the precipitate had fubfided, did not depofit any 
earth on boiling, or become in the leaf! cloudy on the 
addition of fixed alkali ; whereas Rathbone-place 
water in its natural date becomes opake thereby. It 
might perhaps be expended, that the clear liquor 
Should Hill make a precipitate on the addition of fixed 
alkali, though the unneutralized earth is precipitated ; 
as in all probability there is Still a good deal of earth 
remaining in it in a neutralized date. The realbn 
why it does not, feems to be, that the remaining 
earth is mod likely intircly magnefia ; and Epfom 
fait. 
