PHYSIGAL ann LITERARY. 197. 
Wh ftcok care to dilute the vitriolic acid, jn 
order to avoid the heat and ebullition 
which it would otherwife have excited: in 
the water; and I chofe a Florentine flafik, . 
on account of its lightnefs, capacity, and 
shape, which is peculiarly adapted to the 
experiment; for the vapours raifed by 
“the ebullition circulated for a fhort time 
thro’ the wide cavity of the phial, but 
“were foon collected upon its fides, like 
dew, afid none of them feemed to reach 
- the neck, which continued perfectly dry 
‘to the end of the experiment. 
We. now perceive the reafon why crude 
and calcined magnefia, which differ in ma- 
ny refpects from ‘one another, agree how- 
/ever in compofing the fame kind of fal, 
‘when -diflolved in any. particular acid ; 
- for the crude magnefia feems to differ from 
the calcined. chiefly by containing a con- 
fiderable quantity of air, which air is una- 
voidably difiipated and loft curing the 
diffolution. 
FRomM our experiments, it feems proba- 
ble, that the increafe of weight which 
fome meta!s acquire, by being farft diffol- 
ved 
