298 ESSAYS ann OBSERVATIONS. 
cid, is evident, becaufe the fame’ materials, 
without the addition of quick-filver, proper- 
ly treated, yield a good aqua regia which dif- 
folves gold. Or quick-filver is firft diffolved 
in aqua fortis, the folution is evaporated till 
their remains a white, dry, vitriolic body, 
which is to be mixed and rubbed with an 
equal weight of decrepitate fea falt, and fu- 
blimed as before: here likewife the acid of 
fea falt, with a portion of the nitrous, is join- 
ed to the mercury ; for one way of prepa- 
ring an aqua regia, is by pouring aqua fortis 
upon decrepitate fea falt, and drawing off a 
liquor by diftillation, which is in effect done 
in this cafe, only the acid incorporates with 
the quick-filver into a vitriolic form. 
VIII. Tue folvent powersof certain menfirua 
arenct deftroyed in the a& of folution, but 
can be exerted on other bodies; and the men- 
jirua feparated from the diflolved bodies, may 
retain or recover all their former qualities. . 
Tuts property of feveral folvents, will 
be found to obtain, in many more inftances 
than is commonly imagined? Many folvents, 
when they are a@tually diffolving bodies, excite 
a‘ftrong and remarkable effervefcence, with a 
great expanfion, hiffing, bubling, heat and 
fmoke: 
