Opticks 1717 - Up

T R OF. II. THEQR. II.
AU hO??lOgelreaZ Light has itsfrOpW Cahzw 1zI*t-’
Jkwrt~g to its Begme of i?efray$Witj, amf
thnt CoZar~~~ cumot be chaftged by Re~exi0n.r
nrzd Xefr*ucZiom.
N the Experiments of the fourth Propofi tion
of the firfl Rook, whell1 had i‘eparated the
heterogeneous Rays from one another, the Spe-
&rum p 8 formed by the kparated Rays, did
in the progrefs from its endp p on which the’
moft refrangible Rays fell, unto its other end 8,
on which the leait refrangible Rays fell, .appear
tinge.d with this f&es of Colours; violet, indigo,
blue, green, yellow, orange, red, together
with all their intermediate degrees in a continual
Succeflion perpetually varying. So that
there appeared as many degrees of Colours, ~1s
there were forts of Rays dithering in Refrangibility.
E~per. ;, Now that thefeColours could not
be changed by Refra&i,on, I knew by refraAin-g
with a Prifm fometimes one very little part of
this’ Light, fometimes another very little ‘part,
as is defcribed in the twelfth &xperiment of
the firit Book. For by this-Refra&ion the Co;
lour of the Li ht was never changed in the leafi.
If any part 0 fg the red Light was refra&ed, it
remained totally of .the ‘Same red Colour as, before.
No orange, no yellow, no green ,or blue;
no other new ,Cjolour 1x7~ produced -by that
Refia&ion. Neither did the Golour any ways’
change by repeated RefkAions, but continued
always