Opticks 1717 - Up

md t, at the Le
the C~lours pro;
duced in the fi’xperiments are ,no other than
thofe which the Rays had at the Lens before
they enter the compofition of this Beam : And
by confequence that they arife not from any new
modifications of the Light by RefraAions and
I&efkxions , but from the various Separations
and Mixtures of the Rays originally endow’d
with their colour-making qualities.
SO, for infiance, having with a Lens 4+ Inches
broad, and two Prifms on either hand 6+ Feet
difiant from the Lens, made fuch a beam of
corn ounded Light : to examin the reafon of
the 8 olours made by Prifms, I refiaAed this
compounded beam of Light XY with another
Prifm HIK k h, and thereby cait the ufual prifmatick
Colours P QR S T upon the Paper L V
Placed behind. And then by itopping any of
she Colours p, T s, t, at the Lens, I found
that the fame 8 &o’ur would vanilh at the Paper.
So if the purple p was fiopp’d at the
-Lens., the purple P upon the Paper would vadh,
and the ‘refi of the Colours would remain
unalter’d, unlefs perhaps the blue, fo far as
;Come purple latent in it at the Lens migl;t be
feparated from it by the following Refra&ons.
And fo by intercepting the green upon the Lens,
she green R upon the Paper would vanifh, and
fd of the, P& ; which lainly {hews, that as the
white beam of Light R Y was compounded of
feveral Lights varioufl colour’d at the Lens,
fo the Colo~rs which a F terwards emerge out of
it by new R&a&ions are no other than thofe
Q( wk@h its yhitenefs was compounded- The
M3
Refra-