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PHYSICAL ann LITERARY. 257 
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OPALY an ounce of chalk was diffolved 
‘in fpiric of falt, the quantity of which 
was fo adjufted, that the mixture was not 
acid in the leaft degree; and the folutioa 
was thrown into twelve ounces of the cau- 
{tic ley ; which quantity I found, by ex- 
periment, to be fufficient for precipitating 
almoft the whole of the chalk, I now 4l- 
trated this turbid liquor, and laid the 
powder remaining in the paper upon a 
chalk ftone, in order to draw as much of 
the water trom it as pofiible, and thereby 
reduce it to the form of a more den‘e and 
“heavy powder, that it might fubfide the 
_ more perfectly in the following part of the 
experiment. I then mixed it with about 
twenty ounces of pure water in a flafk, 
and, after allowing the powder to fubfide, 
"poured off the water, which had all the 
- qualities of lime-water. And I facceflive- . 
ly: converted eight waters more into lime- 
water, feven of thefe in the fame quanti- 
4 ty, and with the fame management, as 
“th the fir {t. The eighth was likeways in the 
fame quantity; but I allowed it to re- 
‘main with the sel, and fhook it fre- 
: / quently 
