Miner ALOGY,^ 129- 
5. They feparate the akali frorii the fat, 
when they have been united in foap ; which 
effeft is called to turdkj or coagulate. 
6. They are volatile and fubtile, fo as never 
to be obfervable by the naked eye, unlefs 
they are mixed with heterogeneous bodies 
and therefore the figure of the pure mi- 
neral acids cannot be defined but by guefs. 
SECT. cxxi. 
The vitriolic acid, Acidum vitrioli aluminh 
et fulphuris, 
I. The pure vitriolic acid, Acidum vitrioli 
purum. 
Is, in abftraft, confidered as pofiible to 
occur in nature : its qualities, when mixed 
with water, in which it is caught by diftil- 
lation, are as follows. 
1. When mixed with the kaft poflible 
quantity of water, it is of an unditous 
appearance, and is for that reafon im- 
properly called oil of vitriol. 
It has in that ftate a confidetable hea- 
vinefs, viz. in comparifon to water, as 
1700 to 1000. 
3. It diflblves filver, tin, the regulus of 
antimony, and quickfilver *, but, 
4. When mixed with more water, it dif- 
folves zinc, iron, and copper. 
5. It difiblves likewife the calcareous earth, 
and precipitates with it in form of a gyp- 
fum, of which a part fhoots into gyp- 
feousDrufen, Selenites et cryftalli gypfei, 
6. It unites with the earth of quartz, when 
it has been previoufiy diflblved in the 
K ligiiar 
