The Experimental Hiſtory of Colours — Begun
The Third Part
Containing Promiſcuous Experiments — About — Colours
Experiment I.
Illuminated B in Because Ecauſe that, according to the Conjectures I have above propos’d, one of the moſt General Cauſes of the Diverſity of Colours in Opacous Bodyes, is, that ſome reflect the Light mingl’d with more, others with leſs of Shade (either as to Quantity, or as to Interruption) I hold it not unfit to mention in the firſt place, the Experiments that I thought upon to examine this Conjecture. And though coming to tranſcribe them out of ſome Phyſiological Adverſaria I had written in looſe Papers, I cannot find one of the chief Records I had of my Tryals of this Nature, yet the Papers that ſcap’d miſcarrying, will, I preſume, ſuffice to manifeſt the main thing for which I now allege them; I find then Among my Adverſaria, the following Narrative.
October the 11. About ten in the Morning in Sun-ſhiny Weather, (but not without fleeting Clouds) we took ſeveral ſorts of Paper Stain’d, ſome of one Colour, and ſome of another; and in a Darken’d Room whoſe Window look’d Southward, we caſt the Beams that came in at a hole about three Inches and a half in Diameter, upon a White wall that was plac’d on one ſide, about five foot diſtance from them.
The White gave much the Brighteſt Reflection.
The Green, Red, and Blew being Compar’d together, the Red gave much the ſtrongeſt Reflection, and manifeſtly enough alſo threw its Colour upon the Wall; The Green and Blew were ſcarce Diſcernable by their Colours, and ſeem’d to reflect an almoſt Equal Light.
The Yellow Compar’d with the two laſt nam’d, Reflected ſomewhat more Light.
The Red and Purple being Compar’d together, the former manifeſtly Reflected a good deal more Light.
The Blew and Purple Compar’d together, the former ſeem’d to Reflect a little more Light, though the Purple Colour were more manifeſtly ſeen.
A Sheet of very well fleck’d Marbl’d Paper being Apply’d as the others, did not caſt any or its Diſtinct Colours upon the Wall; nor throw its Light upon it with an Equal Diffuſion, but threw the Beams Unſtain’d and Bright to this and that part of the Wall, as if it’s Poliſh had given it the Nature of a ſpecular Body. But comparing it with a ſheet of White Paper, we found the Reflection of the latter to be much Stronger, it diffuſing almoſt as much Light to a good Extent as the Marble Paper did to one part of the Wall.
The Green and Purple left us ſomewhat in ſuſpence which Reflected the moſt Light; only the Purple ſeem’d to have ſome little Advantage over the Green, which was Dark in its kind.
Thus much I find in our above mention’d Collections, among which there are alſo ſome Notes concerning the Production of Compounded Colours, by Reflection from Bodyes differingly Colour’d. And theſe Notes we intended ſhould ſupply us with what we ſhould mention as our ſecond Experiment: but having loſt the Paper that contain’d the Particulars, and remembring onely in General, that if the Objects which Reflected the Light were not Strongly Colour’d and ſomewhat Gloſſy, the Reflected Beams would not manifeſtly make a Compounded Colour upon the Wall, and even then but very Faintly, we ſhall now ſay no more of that Matter, only reſerving our ſelves to mention hereafter the Compoſition of a Green, which we ſtill retain in Memory.