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become VVhitc, wherc thofe os many Colours havc at a grcat Distance tnter-fered. Bur yet for further fatisfaction, the Animadversor may try is he pleafe,the Effects of four or five of such Wedges filled with Liquors of as manyftveral Colours.

Belides all thefe, the Colours of Water-bubbles and orber thin pellucid Sub-stances, afford feveral instances of Whitenefs produc'd by their Mixture ; withone of which I fhall conclude this particular. Let (orne VVatcr, in which a con-venient quantity of Soap or Waffiball is distolved, be agitated into Froth,and, aster that Froth has frood a while without further agitation, till you. iee-the Bubbles, of which it consiils, begin to break, there will appear a great va-rie ty of Colours, ali over the top of every Bubble, if you view them near athandj butif you view them at 16 great a distance that you cannot distinguifhthe Colours öne from another, the Froth will appear perfectly White.

Thus muchconcerning the Defignand Substance oftlic AnirrwdversoFs ConfitderationsThere are yet forne particularsto be taken noticc of, betöre I conclude; asthe Denyal ofthe Experimentum Crucis. On this I chose.to lay.the wholc Streßofmy Discourfej which therefore was the prirjcipal thing to luve been objectedagainst. But I cannot beconvihced of its Infiifhciency by a bare Dcnyal with-oLit alligninga Reafbnfor it, I am apt to believe, it has been misimderstood-stor otherwife it would have preyented theDiscourfes abput Rarefying and Split-ting of Rays; becauleithe design of.it is, to sticw, that Rays of divers Co-löurs conßdered apart, do at Equallncidences suffer Unequal Refractions, with*out being Split, Rarefy’d, or any ways Dilated.,

S«mt ceoftitr^. VI. l. Methinks that the most Important Object ion, which is nude againstco-Mr. Newton by way of Querie, is that, VVhether there be more than two fortslourrfrtmPirisroF Colours. For my part, I believe, that an Hypothefis, that shoidd explaina! 9<5 'ioS6. Mechanically, and by the Nature,of .Motion, the .Colours Yellow and Blue,would be, sufficient for all the reff, in regard that thofe others, heing onlymore deeply charged, (as appears by the Prifms of Mr. Jlookj do produce thedark.or deep Red and Blue, and that of thefe four all Jthe.-othcr Colours.maybe Comuounded.- Neither do 1 lee why Mr. Newton doth not Contenthimfeif with the two Colours, Yellow and Blue; for it will be rmich moreeasie to find an Hypothefis by Motion, thut may explicate thefe two Difteren-ces, than for 16 many Diversities as there are of other Colours. And till hehath found this Hypothefis, sie bath not taught us, what it is wherein consiststhe Nature, and Difference of Colours, but only this Accident ('which certain-ly is ver.y considerable,) of their different Rcfmngibility.

As. for the Composition of White made by ali the Colours together, it maypöstibly be, that Yellow and Blue might also be sufficient for that : Which iswovth while to try; and it may be done by the Experiment which Mr. New-ton prbposeth, by receiving against a Wall of a darkned.Room the Colounsof the Prifrn, and to cast their Rcflected Light upon white Paper, . Here youmust bindet the Colours of the Extrernities, . vff the Red. and Purple, fron»striking. against the Wall, and leaye only the Intermediäre Colours, Yellow,Green, asidfflue, to feeyyhethet the Light of thefe alone wouldnot makethe