heat and vital air. These
substances are of two kinds; the one more simple, the other more
compound.

The most simple kind is composed of two different substances, viz.
phlogiston, with certain specific substances; from which result, on the
one hand, sulphur, and, on the other, proper coal and metals. The more
compound sort, again, is oily matter, produced by vegetables, and
forming bituminous bodies.

The _first_ of these is found naturally combined with almost all
metallic substances, which are then said to be mineralised with sulphur.
Now, it is well known, that this mineralising operation is performed by
means of heat or fusion; and there is no person skilled in chemistry
that will pretend to say, this may be done by aqueous solution. The
combination of iron and sulphur, for example, may easily be performed by
fusion; but, by aqueous solution, this particular combination is again
resolved, and forms an acido-metallic, that is, a vitriolic substance,
after the phlogiston (by means of which it is insoluble in water) has
been separated from the composition, by the assistance of vital air.

The variety of these sulphureo-metallic substances, in point of
composition, is almost indefinite; but, unless they were all soluble in
water, this could not have happened by the action of that solvent. If we
shall allow any one of those bodies to have been formed by the fluidity
of heat, they must all have been formed in the same manner; for there is
such a chain of connection among those bodies in the mineral regions,
that they must all have been composed, either, on the one hand, by
aqueous solution, or, on the other, by means of heat and fusion.

Here, for example, are crystallised together in one mass, 1_st,
Pyrites_, containing sulphur, iron, copper; 2_dly, Blend_, a composition
of iron, sulphur, and calamine; 3_dly, Galena_, consisting of lead
and sulphur; 4_thly, Marmor metallicum_, being the terra ponderosa,
saturated with the vitriolic acid; a substance insoluble in water;
5_thly, Fluor_, a saturation of calcareous earth, with a peculiar acid,
called the _acid of spar_, also insoluble in water; 6_thly, Calcareous
spar_, of different kinds, being calcareous earth saturated with fixed
air, and something besides, which forms a variety in this substance;
_lastly, Siliceous substance_, or _Quartz crystals_. All these bodies,
each possessing its proper shape, are mixed in such a manner as it would
be endless to describe, but