MINERALOGY. 137 
periments, if their qualities had been re- 
garded, in preference to their figures, 
or their native places. 
This may be called Englifli or Epfom 
fait, when it has naturally as equal a co- 
pious portion of the calcareous earth as of 
the artificial one ; but I have, in regard 
to its effe6ts, for which it has been moft 
valued by Glauber, ranked all the lefs 
confiderable varieties of this neutral fait, 
when natural,: under the name of fal mi^ 
rabile. 
SECT. CXXVII. 
B. Acid of common or fea-falt, falis 
communis. 
This acid, confidered in that ftate in which 
it can be had, viz. in mixture with water, 
has the following qualities. 
1. It does not alter the fluidity of water, nor 
confiderably augment Its heavinefs, as the 
vitriolic acid does. 
2. It is fomewhat lefscorrofive and four than 
the faid vitriolic acid. 
3. It flrongly attradts the alcaline falts; but, 
however, is forced to quit them to the vi- 
triolic acid, when that is added. 
4. It diflblves the calcareous earth, and makes 
with it a fubftance, called fal ammoniacum 
fixum. 
5. When expofed to the fire, combined with 
a phlogiilon, it burns with a yellowifh 
green flame. 
6. When highly concentrated and pure, as 
when it is diftilled from common fait mixed 
with pipe clay, it diflblves tin and lead : 
btit 
