I3fi A SYSTEM OF 
a. With the alcali of the common fait, or 
fea-fak, AlcaJi minerali faturatum : Sal mU 
rabile Glauheru 
This is a neutral fait, prepared by na-- 
ture, as well as by art, containing more 
or lefs .of iron, or of a calcareous earth, 
from which arifes alfo fome difference in 
its effeds, when internally ufed. It fhoots 
eafily into prifmatical criftals, which be- 
come larger in proportion to the quantity 
of water evaporated before the criftalli- 
fation. When laid on a piece of burning 
charcoal, or elfe burnt with a phlogifton, 
the vitriolic acid difcovers itfelf by the 
fmell like to the hepar fulphuris. 
It is found in a diffolved ftate in fpring$ 
and wells, and in a dry form on walls, in 
fuch places where aphronitrum has efflo- 
refced through them, and the vitriolic acid 
has happened to be prefent; for inftance, 
where marcafites are roafted in the open 
air. This fait is often confounded with 
the aphronitrvim, or a pure mineral alcali ; 
and a learned difpute once arofe, which of 
thefe falts ought with the greateft propriety 
to be called natron, Baurach veterum^ fal 
mirahile^ or Epfom fait ; whereas it might 
cafily have been decided by chemical ex^ 
celebrated experiments of Lemery, and others, demonftrate, 
?ind from which caufe many volcanos and earthquakes may 
perhaps be deduced, 'Iht puhis pyrcphorus 
alum, intimately united with a phlogiftic fubftance ; in 
the preparing of which, they ought carefully to avoid that 
any iron enters the mixture, becaufe the acid has too ftrong 
an attradlion to the iron, and cannot unite with the phlo- 
gidon which^ however, is quite necelTary in this ope- 
ration, 
perimentSa 
