E 2^1 } 
SECT. XIX, 
After the mineral bodies have beell tried lii tht 
fire by themfelves^ they ought to be melted with 
duxes, to find out if they can be diffolvcd or not, 
and fbrne other phoenomena attending this opera- 
tion. To this purpofe three different kinds of 
falts are ufed as fluxes, viz. Sal Sodee^ Boras^, and 
Sal fufthle microcofmicum (Sedl. xi), 
SEC T. XX. 
The Sal Sodjs is a mineral alcali Well known,’ 
prepared from the herb Kali or Saltwort ; this fak 
is however not much ufed in thefe fniall experk 
ments, its effeds upon the charcoal rendering it, 
for the mod part, unfit for it •, becaufe, as foon as 
the flame begins to a6t upon it, it melts indantly, 
and is almoft wholly attraded by the charcoal. 
When this fait is employed to make any experi- 
ment, but a very little quantity thereof is wanted 
at once, viz. about the cubical contents of an 
eighth part of an inch,, m.ore or Icfs : This is laid 
Upon the charcoal, and the flame blown on it with 
the Blow-pipe; but as this fait commonly is in 
form of a powder, it is necefiary to go on verjr 
fofdy, that the force of the flame may not difpede 
the minute particles of the fait. As foon as it 
begins to melt it runs along on the charcoal al- 
mofl: as melted tallow, and when cold, it is a 
glaffy matter of an opaque dull colour fpread oi^ 
the coal. The moment it is ‘inelted the matter 
which is to be fried ought to be put into it, be- 
caufe otherwife the greateft part of the fait will 
be foaked into the charcoal, and too little of it 
left for the intended purpofe ; the flame ought 
U 2 then 
