such chemical books as
treat upon these operations.

We are probably only acquainted as yet with a part of the metallic
substances existing in nature, as all those which have a stronger
affinity to oxygen, than charcoal possesses, are incapable of being
reduced to the metallic state, and, consequently, being only presented
to our observation under the form of oxyds, are confounded with earths.
It is extremely probable that barytes, which we have just now arranged
with earths, is in this situation; for in many experiments it exhibits
properties nearly approaching to those of metallic bodies. It is even
possible that all the substances we call earths may be only metallic
oxyds, irreducible by any hitherto known process.

Those metallic bodies we are at present acquainted with, and which we
can reduce to the metallic or reguline state, are the following
seventeen:

1. Arsenic.
2. Molybdena.
3. Tungstein.
4. Manganese.
5. Nickel.
6. Cobalt.
7. Bismuth.
8. Antimony.
9. Zinc.
10. Iron.
11. Tin.
12. Lead.
13. Copper.
14. Mercury.
15. Silver.
16. Platina.
17. Gold.

I only mean to consider these as salifiable bases, without entering at
all upon the consideration of their properties in the arts, and for the
uses of society. In these points of view each metal would require a
complete treatise, which would lead me far beyond the bounds I have
prescribed for this work.

FOOTNOTES:

[30] I have not ventured to omit this element, as here enumerated with
the other principles of animal and vegetable substances, though it is
not at all taken notice of in the preceding chapters as entering into
the composition of these bodies.--E.

[31] Perhaps my thus rejecting the alkalies from the class of salts may
be considered as a capital defect in the method I have adopted, and I am
ready to admit the charge; but this inconvenience is compensated by so
many advantages, that I could not think it of sufficient consequence to
make me alter my plan.--A.

[32] Called Alumine by Mr Lavoisier; but as Argill has been in a manner
naturalized to the language for this substance by Mr Kirwan, I have
ventured to use it in preference.--E.

CHAP. XVII.

_Continuation of the Observations upon Salifiable Bases, and the
Formation of Neutral Salts._

It is necessary to remark, that earths and alkalies unite with acids to
form neutral salts without the interventi