MINERALOGY. *a$ 



5. They feparate the alcali from the fat, 

 when they have been united in foap •, which 

 effect is called to 'curdle, or coagulate. 



6. They are volatile and fubtile, fo as never 

 to be obiervable by the naked eye, unlels 

 they are mixed with heterogeneous bodies ; 

 and therefore the figure of the pure mi- 

 neral acids cannot be defined but by guefs. 



SECT. CXXI. 



A. The vitriolic acid, Acidum vitrioii aluminis 

 et fulpburis. 



I. The pure vitriolic acid, Acidum vitrioli 

 purum. 



Is, in abftract, confidered as poffible 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 lead poffible 

 quantity of water, it is of an unctuous 

 appearance, and is for that reafon im- 

 properly called oil of vitriol. 



2. It has in that ftate a confiderable hea- 

 vinefs, viz. in comparifon to water, as 

 1700 to 1000. 



3. It diffolves filver, tin, the regulus of 

 antimony, and quickfilver ^ but, 



4. When mixed with more water, it dif- 

 folves zinc, iron, and copper. 



5. It diffolves likewife the calcareous earth, 

 and precipitates with it in form of a gyp- 

 fum, of which a part moots into gyp- 

 feousDrufen, Selenites et cry fl alii gypfei. 



6. It unites with the earth of quartz, when 

 it has been previoufly diffolved in the 



K liqusr 



