290 ESSAYS anv OBSERVATIONS 
and the former. On the other hand, agua 
fortis and aqua regia appear to be much of the 
fame nature; and the former, by a very {mall 
change, may be converted into the latter ; 
yea, further, they diffolve equally feveral 
bodies, as copper, iron, fpelter, tinglafs : 
yet, it would be erroneous to conclude, that, 
whatfoever body one of thefe liquors dif- 
folves, the other: would diffolve the fame; 
for aqua fortis diffolves filver and not gold, 
and, vice verfa, aqua regia diffolves gold and 
not filver. 
IV. Tue folvent power of fome liquors, 
with refpect to certain bodies, may be in- 
creafed, diminifhed or deftroyed, by a very 
{mall and almoft ene change of the 
liquors. . 
I put two grains of gold into a drachm of 
fpiritus falis marini, and fet the glafs on warm 
fand; after fome hours, I could obferve no 
fenfible change of the bits of gold, in colour ; 
or bulk, nor of the liguor: then I put into ; 
the glafs, as cautioufly as I could, one drop — 
of fpiritus nitr: ; after fome time, 1 found — 
the liquor had affumed a bright yellow, or — 
golden colour, and the gold quite diffolved ; 
for there remained only a few white particles 
at : 
