Opticks 1717 - Up

has itood a little, there will appear to olie that
ild viewit illtently various Colours every where
iii the Surfilces of the feveral Kubbles ; but to
one that fled go fo far off’ that he cannot difj.inguifll
the COIOLKS from one another, the
whole ITrOth will grow white with a perfeit
whi tenefs.
Expw. 15. LaMy, in attempting to corn4
pound a white by mixing the coloured Powders
which P~TI-S ~fe, I confidcr’d that all colour’d
Powders do rupprefs and itop in them a
very confidc~~ble part of the Light by which
they are iIIulninated. ITor they become cOlOur’d
by rcfleCting the Light of their own Colo~rs
more copioufly , and thar of all other Colours
niore fparingly, and yet they do not refle8 the
Light of their own Colours fo copioufly as
white Bodies do. If red Lead, for inftance ,
,and a white Pliper, be placed in the red Light
of the colour’d SpeArummade.in ti dark Chamber
by the RefracCGon of a F,rifin, as is defcribed
in the third Experiment of the firit Rook;
the Paper will app&r more lucid than the red
Lead, and therefore refM% the red-making
Kays more,copioufly than red Lead doth. And
if: they be ’ held in the Light of any other Co-
Iour, .the Light refle&ed by the Paper will exceed
the Light refleCted by the red Lead in a
much greater proportion. And the like happens
in Powders of other Coloilrs. And therefore
by mixing fuch Powders we are not to expe&
a flrong and full white, I‘uch is is that of
Paper, but ibme dusky obfcure ones iach as.
might arii’e from 8 mixture Of light and dark-
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_L nefs,