2o5 ESSAYS AND OBSERVATIONS 



ry ftrong, was lighter than water, and float- 

 ed upon it Hke fpirit of wine. 



I next inquired into the truth of the fifth 

 propofition, in the following manner. 



Two drams of epfom-falt were difTolved in 

 a fmall quantity of water, and thrown into 

 two ounces of the cauftic-ley ; the mixture in- 

 ftantly became thick, like a decodtion of 

 ftarch or barley, by the magnefia, which 

 was precipitated. I then added fpirit of vi- 

 triol by degrees, until the mixture became 

 perfedrly clear, or the whole of the magnefia 

 was again diffolved j which happened with- 

 out any eftervefcence or emiffion of air. 



Half an ounce of chalk was difTolved in 

 fpirit of fait, the quantity of which was fo 

 adjufted, that the mixture was not acid in 

 the leaft degree j and thefolution was thrown 

 into twelve ounces of the cauftic ley ; which 

 quantity I found, by experiment, to be fuffi- 

 cient for precipitating almoft the whole of the 

 chalk. I now filtrated this turbid liquor, and 

 laid the powder remaining in the paper upon 

 a chalk-ftone, in order to draw as much of 

 the water from it as pofiible, and thereby re- 

 duce it to the form of a more denfe and hea- 

 vy powder, that it might fubfide the more 



perfedly 



