f boyling Alabaster; which
is explicated. An explication of the contracting of heated Glass upon
cooling. An explication how the parts of the Glass become bent by sudden
cold, and how kept from extricating themselves by the contignation of the
Glass drop; which is further explicated by another Experiment made with a
hollow Glass ball: the reason of the flying asunder of the parts further
explicated: that 'tis probable these bodies may have many flaws, though not
visible, and why: how a gradual heating and cooling does put the parts of
Glass, and other hardned bodies, into a looser texture._

Observ. 8. Of Fiery Sparks.

_The occasion and manner of making this Experiment: divers Observations set
down in order to the finding out the reasons: some conjectures concerning
it, which are endeavoured to be explicated and confirm'd by several
Experiments and Reasons: the _Hypothesis_ a little further explicated. Some
Observations about the Globular Figure: and an Experiment of reducing the
filings of Tin or Lead to exactly round Globules._

Observ. 9. Of Fantastical Colours.

_The texture of _Muscovy_ Glass; its Figures: what other Bodies are like
it: that it exhibits several colours, and how: several Observations and
Experiments about those colours: the reason why on this occasion the nature
of colours is inquir'd into. A conjecture at the reason of these colours
explicated by several Experiments and Reasons: First, by continual cleaving
the Body till it become colour'd. Secondly, by producing all kinds of
colours with two flat Plates of Glass. Thirdly, by blowing Glass so thin in
the Lamp, till it produce the same effect. Fourthly, by doing the same with
Bubbles of divers other transparent Bodies: the reasons of the colours on
nealed Steel, where by the way the causes of the hardning and tempering of
Steel, endeavour'd to be shewn and explicated by several Reasons and
Experiments: the reason of the colours on Lead, Brass, Copper, Silver, &c.
other Instances of such colour'd bodies in animal substances: several other
distinguishing Observations. _Des Cartes Hypothesis_ of Colours examin'd.
An _Hypothesis_ for the explication of light by motion, indeavoured to be
explicated and determined by several Reasons and Experiments: three
distinguishing Properties of the motion of light. The distinguishing
Properties of a trasparent _Medium_ [that there seems to be no Experiment
that proves the Instantaneous motion of light] the manner