e capable of diluting: some of mixing, what a
strange variety may thereby be produc'd._

Observ. 11. Of the Figures of Sand.

_Of the substances and shapes of common and other Sands: a description of a
very small Shell._

Observ. 12. Of Gravel in Urine.

_A description of such Gravel, and some tryals made with it, and
conjectures at its cause._

Obser. 13. Of Diamonds in Flints.

_A description and examination of some of them, explicated further by
Cornish Diamonds: several Observations about reflection and refraction:
and some deductions therefrom; as an explication of whiteness; that the Air
has a stronger reflection then Water. How several Bodies may be made
transparent: an explication of the _Phaenomena_ of _Oculus Mundi_. Of the
regular Geometrical Figures of several Bodies: an hypothetical explication
mentioned: the method of prosecuting this inquiry._

Observ. 14. Of frozen Figure.

_The Figures of hoar Frost, and the Vortices on windows: several
Observations on the branched Figures of Urine: the Figures of _Regulus
Martis stellatus_, and of Fern. Of the Figures of Snow. Of frozen water._

Observ. 15. Of Kettering Stone.

_A description of the Figure of the Particles, and of the Pores, and of the
Contexture. Several Observations and Considerations thereupon: some
Conjectures about the _medium_ and propagation of light, and the
constitution of fluid and transparent Bodies. Several Experiments to prove
the porousness of Marble, and some other Stones. An account of some
Experiments to this purpose made on an _Oculus Mundi_: some other
Considerations and Experiments about the porousness of Bodies: some other
Considerations about the propagation of light and refraction._

Observ. 16. Of Charcoal.

_Of two sort of Pores to be found in all Woods and Vegetables; the shape of
them; the number, thickness, manner and use of these Pores. An explication
of the _Phaenomena_ of Coals. The manner of charring Wood, or any other
body. What part of Wood is combustible. An _Hypothesis_ of fire explicated
in twelve particulars, wherein the Action of the Air, as a _Menstruum_ in
the dissolution of all sulphureous bodies, is very particularly explicated,
and some other Considerations about the Air proposed: the examination of a
piece of _Lignum fossile_ sent from _Rome_, and some Conclusions thence
deduc'd._

Observ. 17. Of Wood, and other Bodies, petrified.

_Several Observations of divers kinds of these substances. A