I o 6 Mijcellanea Curio fa. 



this Analogy 'twixt Colours, and Refrarigibility, 

 is very precife and ftn& ; the Rays always either 

 exactly agreeing in both, or proportionally difc 

 agreeing in both. 



3. The Species of Colour, and Degree of Re- 

 frangibility proper to any particular fort of Rays, 

 is not mutable by Refraction, nor by Reflection 

 from Natural Bodies, nor by any other Caufe, 

 that I could yet obferve. When any one fort 

 of Rays hath been well parted from thofe of o- 

 ther kinds, it hath afterwards obftinately retained 

 its Colour, notwithstanding my utmcft Endea- 

 vours ro change it. I have refra&ed it with 

 Prifms, and reflected it with Bodies, which in 

 Day- light were of other Colours ; 1 have inter- 

 cepted it with the coloured Film of Air interce- 

 ding two comprefTed Plates of Glafs , tranfmitted 

 it through colour'd Mediums, and through Me- 

 diums irradiated with other forts of Rays, and 

 dirafly terminated it, and yet could never pro« 

 duce any new Colour out of it. It would by 

 contracting and dilating become more brisk, or 

 faint, and by the lofs of many Rays in fbme 

 Cafes very obfcure and dark; but I could never 

 fee it chang'd in fpecie. 



- 4. Yet feeming Tranfmutations of Colours 

 may be made, where there is any mixture of di- 

 vers forts of Rays. For in fuch mixtures, the 

 component Colours appear not, but by their mu- 

 tual allaying each other, conftitute a midling 

 Colour. And therefore, if by Refraction, or 

 any other*of the aforefaid Caufes, the difform 

 Rays, latent in fuch a mixture, be feparated, 

 there {hall emerge Colours different from the 

 colour of the Compofition. Which Colours are 

 not new generated, but only , made apparent 

 by being parted ; for if they be again intirely 



mix'd 



