H4 
A SYSTEM OF' 
This is fo ftrongly united with the 
calcareous earth, that the latter enters 
with it into the very criftals of the fait : 
though by repeated folutions the earth 
is by degrees feparated from it, and falls 
to the bottom after every folution. It 
grows in form of white froft on walls, 
^ and under vaults, and in places where it 
cannot be wafoed away by the rain. 
When it contains any confiderable quan- 
tity of the calcareous earth, its criftals 
become rhomboidal, a figure which the 
calcareous earth often afllimes in Ihoot- 
ing into criftals : but when it is purer, 
the criftals ftioot into a prifmatical figure. 
This is a circumftance which neceflarily 
muft confufe thofe who know the falts 
only by their figure, and fhews, at the 
fame time, how little certainty fuch ex:^ 
ternal marks afford in a true diftinclion 
of things. This fait is therefore very 
often confounded with the fal Imirabile. 
SECT. CXXXVIIL 
3. Saturated with mineral acids, [Akali 
falls communis acidis miner alihus ad faturi^ 
tatem mixtum. Neutral falts, Salia media^ 
falia neutra. 
With the acid of fea-falt, common fait, 
fea-falt, Sal commune. Se6l. cxxix. 
i. With the vitriolic acid, Sal mirahile, 
Seft. cxxvi. 
SECT. 
