29 2

Plate

XXXIV.

Of Light and Colours.

When a Ray of Light HC falls on anyplain, convex, or concave Surface, as A 8,

Particles contiguous to each other, the Light would pa!*from one to another (and so through the whole) with'out Reflection, as we find by Experiment it will p a * sthrough several contiguous Pieces of polished Glai*»and thus produce Transparency.

4. But if the Particles do not touch in such manN^to leave the Interstices or Pores exceeding sinaso

as

there will be a Reflection of Light at every Pore froi®the Air which it there meets with, as being a Mediu 111of different Density. For it is known by Experimentthat though a Ray of Light will pass from one Piece otGlass to another, that is contiguous without Reflectionyet will it not pass from the Glass through the cop'tiguous Air without being in part reflected ; cord e 'quently where the Pores are large and very numeron-)there the Reflection of the Light will be so great up°^the whole, as to cause a total Diflipation and Loss 0the Light that enter’d the Body, and so render 1opake.

5. This is confirmed by taking ten Pieces of cl e ^

Glass, and laying them one upon another over a L eaof Print, quite dry, and having only Air between the 111 jthen taking ten other Pieces of the fame Glass, a Lputting them into Water, so that it may fill all th c ^Interstices, and then laying them on the same prin^Paper by the other, a Person looking through each ^fee the Print or reading much more distinct, clear, a)1bright, through the latter Pieces than through the >° ^mer ; the Rays being more regularly transmitted thro 1 ^them where the Density of the Parts is not so uneci l,a ’and also with much less Reflection than through jother, where the Light undergoes a considerable!flection at every Interstice or Plate of Air between fGlasses. _ , r

6. ’Tis hence also that transparent Bodies aredered opake by separating their Parts and rendering ^ ^more porous; thus Beer before it is raised into f s0 j S