of Magnefian Earth. 46^ 
a proof of the acidity of that gas. Perhaps the 
ingenious Chemift, who prepared the other por¬ 
tion of Magnefia, not adverting to this circum- 
ftance, or juftly not confidering it as materially 
affefting the medicinal properties of the Magnefia, 
though it would greatly alter its chemical quali¬ 
ties, might have ufed his Lixivium, foon after 
filtration, and, by this means, the extraneous 
Earth might have been introduced into the 
Magnefia, and have affected its fufibility. 
Dr. Black had faid, in his excellent Effay on 
Quicklime and Magnefia, that Calcined Mag¬ 
nefia, diffolves in the vitriolic, nitrous, marine, 
and acetous acids, and forms with them Salts, 
fimilar to thole produced by the uncalcined 
earth with the fame acids. But Mr. Monch, 
a German apothecary, has afferted, that though 
he poured half an ounce of ftrong vinegar on 
twenty grains of Calcined Magnefia, and fuf- 
fered the mixture to ftand for twenty-four hours, 
only feven grains of the Magnefia were diffolved ; 
and that he was unable to diffolve more than 
the fame quantity, by digefting, in a moderate 
heat, an equal portion of Calcined Magnefia, 
in half an ounce of a mixture confiding of one 
part of firong vitriolic acid and fix of water, for 
twenty hours. And, what is ftill more extraor¬ 
dinary, he could diffolve only nine grains out 
of twenty by boiling for a conliderable time, 
in an ounce of the fame diluted acid. But in 
H 3 the 
