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 of the propagation of light through them.  Of the homogeniety and heterogeniety of transparent Mediums, and what effects they cause on the Rayes of light, explicated by a Figure:  an Examination of the refraction of the Rays by a plain Surface, which causes Colours.  An Examination of the like effects produced by a spherical Surface:  the use that may be made of these Experiments, for the examination of several Hypotheses of Colours. Des Cartes Hypothesis