1000000031

>13°

th: eolour: of

l,omo~<ncou,lig1a1

are to be

eh.og:

d by any

rcf nélton.

R e.1 lo.J, \Vh.o it i, viewed io open day-light, or \Vheo

heteroge neou, rays

f.ll

upoo it. wiU like\ViCe be red, if

it i, p!aeed

homogeoeou, red light: but red lead. \Vhen

i, is p\.¡eeJ in ,n y olher

Con

of hornogeoeou. light. wiU

h.ve

the Came eolour with the rays that faU upon it and

are r

<Re09.ed

froOl it: if it is plaeed io yello\V homoeene–

ou, líght. it \ViII b. yeUow; if in green líght. it will be

greeo; or if in blue light. i, \Viii be blue_ ConCequently

,he rcR:dioo of the ray' from ,he red lead

m.ke

no al

te–

ration in their colour;

ror

it did, rays of any

ron

re·

fi eéled from ,he lead \Vould be of ,be fame eolour. fa tha!

it would appear red in \Vhatever fort of ligh, i, was pla–

ced_ The

f.me

that i, here faid of red le.d. i, uue of

aoy other fub!!aoee of aoy other eolour_ GraCs, whieh

'is green

ei~her

in opeo

day·light

or in homogeneous greco

I;ght. \ViII not ehauge the eolour of .oy homogeoeous " ys

by refteéling them, but will itCelf have the f,me eolour

",ith the r.y' in whieh it i, pla.eed; it will be red in red

¡ight. or blue in blue lighl, or yellow in yellow light_

Fronl-hence.,e may eonelude, by the \Vay. tba! a body

of any particillar colour, not becaufe

refleéls no othcr

,..y. but thoCe of tha! particular eolour, bUl beeauCe it re–

!leds thoCe more eopiouOy and others more fpariogly_

R ed lead, as it appears red in red light.

in greeo light

it 'ppea.. green. or io blue light it appea" blue: eoo–

fequeotly it reUeds rays of theCe COrlS. aod in the Came

manner .it might be (hewn to reReét all other Corts of rays.

Hut then the red eolour of red lead. wheo it is plaecd in

red light. is mueh brighter than any other eolour will be

!hat

it pu" on by being plaeed in another fort of light :

cooCequcotly it reReds red rayo more eopiouOy than aoy

other (ort of rays ; and

ror

this reaCon, when

is placed

in opeo day-light. \Vhere it reReds

,11

CorlS

of rays at once,

lhe red ray' are fa much more numerau! Ihan lhe

rdl,

m.ke

the whole mixture of their o\Vn eoloor.

Colourf maJ

produc<d 6J cOINpo/irion. 'Which ¡hall in

IIpp.ar

",,«

¡ii. Ih. colour

h'l1IogmfDuf lighl :

huI Ihm

Ih.ft

cOlllpound colo/lr¡ will

al/.nd 6J

n –

j'r.nion_

WHEN,

means

o'~t\'O

holts in

the

window·lhuner

<>f a dark room .nd of two priCms, two oblong eoloured

1'i8ures are produeed; if a circular pieee of \Vh¡te paper

fo plaeed that the red Hght of one pidure and the

)'cI–

low light o( the other may f.o l upon it, this mixture will

produce an orange colour, that in appearance will be like

.he primuy orange eolour. But betw«n . he Gmple and

compound colou" tho\lth they are alike in appearance,

there will be this diffc.:rcnce; if.the circular piece arpaper,

when

enligh[cned wilh com pound orange. is viewed

through a priCm. the rays \ViII be found to be di{fereotly

refr.ngible. and they \ViII . hy the rdr.d ion of the priCm.

Cep.rated from one another, that the paper Ceen

througb it \ViII appear . s two eirel. s. one of whieh will

be red ,nd the o.her ycJ low; where.s. if the C. me paper,

hen

is cAlightened

Wilh

limpie or primary orange, is

vicwed in like

m~nner

lh rough

a prifm. the rays will be

f ound to be rquall y refrangible, ,nJ the p'per will appe. r

ahrot1¡¡h lhe priCOl, as it d oes tO the naked eye, to be ene

oraoge_eoloured eirele ditlindly lerminaled ,11 round_

Arter the fame manner ol"er homogeneous colour5, al

blue and yellow, when mixcd together, will j!roduce a

a new compound colour like the intermediate homogenee

ous green eolou, in appearanee. Rut then the uys of

this eompound green wdl not be all of .hem equally re–

frangible,

the ray' of ,he fimple or primary green co–

Jou r are.

'rh. 'Whi/tnif! oj' rhe j'un'f ligM

j¡

compound.d

all In.

pril1ulrJ coJourJ mi.:utl in

due prtJporlion.

LE"

the oblong eoloured pidure (No.

37.)

fall upo.

the convex len. MN; aod tbeo

,11

,he

"y,

\Vhieh are

fcpara!ed from on. aoother

PT will be eolleded to–

gether by p,lling through the lens, , nd will meet

its fo–

cus

fueh

a manller as to form a round p¡aure of the

fun upoo a \Vhite paper

DE.

This rouod piaure. whieh

confitls of uy. of aJl rorlS. of red. orange, yellow, blue.

¡reeo, indigo, and violet, is white. And this whitene(s is

eompounded of

, 11

the primary eolours mixed together.

None of the rays ehange their eolour by being mixed .,ith

the ren; eaeh (ort retains the (ame colour arter

is mixed

with the reff th" it h.d before; oei,her the red

"Y',

nor

the orange, oor the yellow, nor the blue', .nor

the

grecD,

Dar the ¡ndigo,

nor

the violet,

are

made white

by beina:

mixed with the retl at .he foeus; but though none of the

parlS are white, yet the whole mixture is whitc.

T "at the whileneCs at lhe foeu.

arifes from a mixture

, 11

the

prim.ry

eolou rs. is evideót. For if aoy of the

eolouTS are intereepted at the lens. the foeus lo(es ¡es whitee

[leCs. and becomes of that calour whith ari(es from

mix–

ture of thoCe whieh ¡re no",intereepted. '!ñu. if.1I the

uys at PTare intercepted except the yellaw. tbe orange.

aod ,he red, the foeu. \ViII not be white. but will be o–

raoge-eoloured_ If all the rays are inlercepted at PT. ex–

cept lhe blue, the greeo. aod the yellow, the-foeu. will

then be greeA. The orange in one caCe, and (he green iD

the Olher cafe,

the compound colour arifing from

mix–

ture of thoCe rayo whieh are no' intereepted. And in

either cafe,

the rays that \Vere intercepted are agaio

r"ffered to .paCs throu¡¡b the len., the (oeu. will reeoyer

ilS whiteneC•.

may be more difficuh to /hew Ihat the ray'. whes

they are all of them mixed at Ihe foeu,s. retain their pro–

per eoloun. and are none of them white though the

compound mixture

white. To make this out, Jet the

p'per be removed from

DE.

where all the rays are mi,,–

ed upon

at G, to

de,

where it will receive the uys,

.fter they have ero!T.d one ano.her at the foeus. and

having got beyond it diverge .g. in. In this poGtioo of the

the paper, becaufe the rays that were mixed at the focus

have diverged from theoee. and are again Ceparated f,ol1l

one another. the oblong eolou red pie)ure will .ppe., a–

gain .t

/p.

fa that the red eolour T. whieh was the low–

etl at the lens. will be the highetl " the p'per

d, .

But

lhough the eolours are thus inverted by palling the foeu••

yet all of them appear

IP;

\Vhieh \Vould have becn

impollible, if eaeh Cort of r'Y" by being mixed with ,he

rd l a! the foeus. had lotl their eolour. ,nJ had be.o m,Je

white. N or indeed is

,he

colour of any

(un

of ra)',

all

ehanged by beiog mixed \Vilh lhe ren al the foeus; bul

the