r lfyn Mr. Keir’s Experiments and Obfervahons on 
which feem deductible from the fafts related; and, laftly, by 
concluding with fome reflexions relative to the theory oj metallic 
dijfolution and precipitation. 
• part 
I. 
0*2 the effects of compounding the vitriolic and nitrous ac.ds, under 
upon O' dilution of mob. 
SECTION FIRST* 
v 
On the mixture of oil of vitriol and nit) e. 
i. The properties of the feveral acids, in their feparate* 
Rates, have been inveftigated with confiderable mduhry and 
fuccefs; and thofe of one compound, aqua regts, are we 
known on account of its frequent ufe in diffolvtng gold : yet 
not only various other combinations of different acids remain 
to be examined ; but alfo the changes of properties to which 
thefe mixed acids are fubjeft, from the difference of circum- 
ftarices. efpecially thofe of concentration , temperature, and of 
that quality which is called, properly or improperly, phhgiflt- 
cation, are fubjeffs ftill open for enquiry. ■ 
2 . As 1 (hall have frequent cccaiion to fpeak ct the phloqiju 
cation and dephlogiflicvtion c£ acids, I .wife to premife, that by 
thefe terms I mean only certain flates or qualities of _ thofe 
bodies but without any theoretical reference. Thus vitriolic 
acid may be faid to be phlogifticated by addition of fulphur or 
other inflammable matter, by which it is. converted into iol- 
phureous acid, without determining whether this 
6 ' CaU £ 
