3$2 THE VIRTUES OF LIME-WATER 
is by no means probable, that the fait in the foap-leys, which has 
before fuflained the a&ion of quick-lime without being converted 
into an earthy powder, will fuffer this change by the much weaker 
aftion of lime-water. 
3. If the white powder precipitated upon mixing fait of tartar 
with lime-water, proceeded from the fait, a folution of this fait in 
water fhould be rendered turbid and milky, and produce a greater 
precipitation, by having a piece of calcined oifter-fhell immerfed 
in it, than- by being mixed with lime- water ; which however is not 
the cafe. For, having diffolved a dram and a half of fait of tartar 
in fomething more than two ounces of water, and filtered the fo¬ 
lution through grey paper, I immerfed in it three or four pieces 
of calcined oifler-lhells, weighing about two drams ; a hiding noife 
immediately enfued, and a good many air-bubbles arofe, but the 
liquor remained equally pellucid as before ; nor was there any tur¬ 
bid milky appearance in this ley, during four days that it flood 
on the lime, and fcaree any obfervable precipitation of the fait 5 I 
fay obfervable, becaufe it was not eafy to diflinguifh a fmall preci¬ 
pitation from the lime-powder, a little of which fell from the fhells 
to the bottom of the glafs. 
4. When two or three drops of lime-water fall into a folution 
of potafh or fait of tartar, they become immediately white ; but this 
appearance fbon after vanifhes, becaufe fo fmall a quantity of 
lime-water affords too little earthy matter to be vifible when dif- 
perfed through the whole folution of the fait. If an ounce of lime- 
water mixed with fait of tartar gives only a grain of calcarious 
matter, one drop will not give t-|ö- part of a grain, which is too 
fmall to be vifible, when it falls to the bottom of the glafs in the 
form of a powder. But on the other hand, a few drops of a fo¬ 
lution of fait of tartar or potafh, let fall into a glafs full of lime- 
water, render the whole turbid and milky, and precipitate a white 
powder ; becaufe a very little of the folution is fufhcient to fepa- 
rate a confiderable quantity of calcarious matter from the wa¬ 
ter. 
When