imes when the Oyls of some Spices and of Anniseeds &c. are Distilled in a
Limbec with Water, the Water (as I have several times observ'd) comes over
Whitish, and will perhaps continue so for a good while, because if the Fire
be made too Strong, the subtile Chymical Oyl is thereby much Agitated and
Broken, and Blended with the Water in such Numerous and Minute Globules, as
cannot easily in a short time Emerge to the Top of the Water, and whilst
they Remain in it, make it, for the Reason newly intimated, look Whitish;
and perhaps upon the same Ground a cause may be rendred, why Hot water is
observ'd to be usually more Opacous and Whitish, than the same Water Cold,
the Agitation turning the more Spirituous or otherwise Conveniently
Dispos'd Particles of the Water into Vapours, thereby Producing in the Body
of the Liquor a Multitude of Small Bubbles, which interrupt the Free
passage, that the Beams of Light would else have Every way, and from the
Innermost parts of the Water Reflect many of them Outwards. These and the
like Examples, _Pyrophilus_, have induc'd me to Suspect, that the
Superficial Particles of White bodies, may for the Most part be as well
Convex as Smooth; I content my self to say _Suspect_ and _for the most
part_, because it seems not Easie to prove, that when Diaphanous bodies, as
we shall see by and by, are reduc'd into White Powders, each Corpuscle must
needs be of a Convex Superficies, since perhaps it may Suffice that
Specular Surfaces look severally ways. For (as we have seen) when a
Diaphanous Body comes to be reduc'd to very Minute parts, it thereby
requires a Multitude of Little Surfaces within a Narrow compass. And though
each of these should not be of a Figure Convenient to Reflect a Round Image
of the Sun, yet even from such an Inconveniently Figur'd body, there may be
Reflected some (either Streight or Crooked) Physical Line of Light, which
Line I call Physical, because it has some Breadth in it, and in which Line
in many cases some Refraction of the Light falling upon the Body it depends
on, may contribute to the Brightness, as if a Slender Wire, or Solid
Cylinder of Glass be expos'd to the Light, you shall see in some part of it
a vivid Line of Light, and if we were able to draw out and lay together a
Multitude of these Little Wires or Thrids of Glass, so Slender, that the
Eye could not discern a Distance betwixt the Luminous Lines, there is
little doubt (as far as I can guess by a Tryal purposel