IQ A SYSTEM OF 
The First Order. 
The Calcareous Kinds, Terr^ Calcare^, Thefe, 
when pure, and free from heterogeneous mat- 
ters, have the. following qualities common to 
them all : 
1. That they become friable, when burnt in 
the fire, and afterwards fall into a white 
powder. 
2. That their falling into powder is promoted, 
if, after being burnt, they are thrown into 
water, whereby a ftrong heat arifes, and a 
partial folution, 
3. They cannot be melted by themfelves, or 
per fe^ into glafs in the ftrongeft fire. 
4. When burnt, they augment the caufticity 
of the lixivium of potaflies. 
5. They are diflblved in acids with effervefi 
cence, in the following manner ; 
a. The acid of vitriol partly unites with 
them, and forms a precipitate, which is 
a gypfeous earth, and partly fhoots into 
felenitical cryftals with that which is kept 
difiblved, after a due evaporation, 
convex furface metals take after being melted, is a quality 
not particularly belonging to them, becaufe every thing that 
Is perfedly Huid in the fire, and has no attradlion to the vef- 
fel in which it is kept, or to any added matter, takes the fame 
figure ; as we find the borax, fal fajthile microcofmicum^ and 
others do, when melted upon a piece of charcoal : therefore, 
with regard to all that has been faid, it is hardly worth while 
to invent fuch definitions as fliall include feveral fpecies at 
once 5 we ought rather to be content with perfeftly knowing 
jthem feparately however, as this is to be an Efiay towards 
forming a Syftem, I have endeavoured, in moil parts, to fol- 
low the ufual rules. 
■h. With 
