288 ESSAYS ann OBSERVATIONS 
the fitnefs of fuch liquors to diffolve different 
fubftances. 
Iron and copper, the hardeft of the metals, 
which require the greatef{t force to extend 
them, and the ftrongeft fire to bring them to 
fufion, will be corroded and diffolved by li- 
quors moft harmlefs to the human body ; as 
vinegar, juice of lemons, a folution of tar- 
tar, rhenifh wine, nay moift air: whereas 
quick-filver, whofe particles are fo mobile, 
eafily feparable and diffipated by a moderate 
heat, and tin, which is very foft and eafily 
melted, ,require more corrofive menjtrua. 
Coral, and fome of the hardeft gems, will be 
better diflolved in a weak vegetable acid, than 
in a much ftronger one of the mineral kind. 
Oleum vitrioli, fpiritus nitri, or aqua fortis, 
the moft ponderous and ccrrofive of the a- 
cid liquors, cannot diffolve bees-wax or crude 
fulphur, which will readily relent in the 
mild and foft oil of olives; fal tartari, or o- 
leum tartari, p. d. is almoft equally corrofive, 
with regard tothe human body, as agua fortis : | 
yet the folvent powers of thefe liquors, with 
refpect to other fubftances, are moft oppo- 
fite. 
Ill. Tue 
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