Experiments and considerations touching colours first occasionally written, among some other essays to a friend, and now suffer'd to come abroad as the beginning of an experimental history of colours / by the Honourable Robert Boyle ...

CHAP. I. THe Author shews the Reason, first of his Writing on this Subject (1.) Next of his present manner of Handling it, and why he partly declines a Methodical way (2.) and why he has partly made use of it in the History of Whiteness and Blackness. (3.)

Chap. 2. Some general Considerations are pre∣mis'd, first of the Insignificancy of the Observa∣tion of Colours in many Bodies (4, 5.) and the Importance of it in others (5.) as particularly in the Tempering of Steel (6, 7, 8.) The rea∣son why other particular Instances are in that place omitted (9.) A necessary distinction about Co∣lour premis'd (10, 11.) That Colour is not Inhe∣rent in the Object (11.) prov'd first by the Phantasms of Colours to Dreaming men, and Lu∣naticks; Secondly by the sensation or apparition of Light upon a Blow given the Eye or the Distemper

of the Brain from internal Vapours (12.). The Author recites a particular Instance in himself; another that hapn'd to an Excellent Person related to him (13.) and a third told him by an Inge∣nious Physician (14, 15.) Thirdly, from the change of Colours made by the Sensory Disaffected (15, 16.) Some Instances of this are related by the Author, observ'd in himself (16, 17.) others told him by a Lady of known Veracity (18.) And others told him by a very Eminent Man (19.) But the strange Instances afforded by such as are Bit by the Tarantula are omitted, as more properly deliver'd in another place. (20.)

Chap. 3. That the Colour of Bodies depends chiefly on the disposition of the Superficial parts, and partly upon the Variety of the Texture of the Object (21.) The former of these are confirm'd by several Persons (22.) and two Instances, the first of the Steel mention'd before, the second of melted Lead (23, 24.) of which last several Observables are noted (25.) A third Instance is added of the Porousness of the appearing smooth Surface of Cork (26, 27.) And that the same kind of Porousness may be also in the other Colour'd Bodies; And of what kind of Figures, the Super∣ficial reflecting Particles of them may be (28.) and of what Bulks, and closeness of Position (29.) How much these may conduce to the Generation of Colour instanc'd in the Whiteness of Froth, and in the mixtures of Dry colour'd Powders (30.) A further explication of the Variety that may be in the Superficial parts of Colour'd Bodies, that may cause that Effect, by an example drawn from the Surface of the Earth (31.) An Apology for

that gross Comparison (32.) That the appear∣ances of the Superficial asperities may be Varied from the position of the Eye, and several Instances given of such appearances (33, 34, 35.) That the appearance of the Superficial particles may be Varied also by their Motion, confirm'd by an Instance of the smoaking Liquor (35.) espe∣cially if the Superficial parts be of such a Nature as to appear divers in several Postures, explain'd by the variety of Colours exhibited by the shaken Leaves of some Plants (36.) and by change∣able Taffities (37, 38, 39.) The Authors wish that the Variety of Colours in Mother of Pearl were examin'd with a Microscope (40.) And his Conjectures, that possibly good Microscopes might discover those Superficial inequalities to be Real, which we now only imagine, with his reasons drawn partly from the Discoveries of the Teles∣cope, and Microscope (41.) And partly also from the Prodigiously strange example of a Blind man that could feel Colours (42.) whose History is Related (43, 44, 45.) The Authors conje∣cture and thoughts of it (46, 47, 48, 49.) and several Conclusions and Corollaries drawn from it about the Nature of Blackness and Black Bodies (50, 51, 52.) and about the Asperities of seve∣ral other Colour'd Bodies (53.) And from these, and some premis'd Considerations, are propos'd some Conjectures; That the reason of the several Phae∣nomena of Colours, afterwards to be met with, depends upon the Disposition of the Seen parts of the Object (54.) That Liquors may alter the Colours of each other, and of other Bodies, first by their Insinuating themselves into the Pores, and

filling them, whence the Asperity of the Surface of a Body becomes alter'd, explicated with some Instances (55, 56.) Next by removing those Bodies, which before hindred the appearance of the Genuine Colour, confirm'd by several examples (57) Thirdly, by making a Fissure or Separa∣tion either in the Contiguous or Continued Parti∣cles of a Body (58.) Fourthly, by a Ʋnion or Conjunction of the formerly separated Particles; Illustrated with divers Instances of precipitated Bodies (59.) Fifthly, by Dislocating the parts, and putting them both into other Orders and Po∣stures, which is Illustrated with Instances (60, 61.) Sixthly, by Motion, which is explain'd (62.) And lastly, and chiefly, by the Ʋnion of the Saline Bodies, with the Superficial parts of another Body, whereby both their Bigness and Shape must necessarily be alter'd (63, 64.) Explain'd by Experiments (65, 66.) That the Colour of Bodies may be Chang'd by the concurrence of two or more of these ways (67.) And besides all these, Eight Reflective causes of Colours, there may be in Transparent Bodies several Refractive (68, 69.) Why the Author thinks the Nature of Co∣lours deserves yet a further Inquiry (69.) First, for that the little Motes of Dust exhibited very lovely Colours in a darkned Room, whilst in a con∣venient posture to the Eye, which in other Postures and Lights they did not (70.) And that though the smaller Parts of some Colour'd Bodies are Trans∣parent, yet of others they are not, so that the first Doubt's, whether the Superficial parts create those Colours, and the second, whether there be any Re∣fraction at all in the later (71, 72, 73.) A

famous Controversie among Philosophers, about the Nature of Colour decided. (74. 75.)

Chap. 4. The controversie stated about Real and Emphatical Colours (75, 76.) That the great Disparity between them seems to be, partly their Duration in the same state, and partly, that Genuine Colours are produc'd in Opacous Bodies by Reflection, and Emphatical in Transparent by Refraction (78.) but that this is not to be taken in too large a Sense, the Cautionary instance of Froth is alleged and insisted on (78, 79.) That the Duration is not a sufficient Characteristick, exemplify'd by the duration of Froth, and other Emphatical Colours, and the suddain fading of Flowers, and other Bodies of Real ones (80.) That the position of the Eye is not necessary to the discerning Emphatical Colours, shew'd by the seeing white Froth, or an Iris cast on the Wall by a Prism, in what place of the Room soever the Eye be (81.) which proceeds from the specular Re∣flection of the Wall (82.) that Emphatical Co∣lours may be Compounded, and that the present Discourse is not much concern'd, whether there be, or be not made a distinction between Real and Em∣phatical Colours. (83.)

Chap. 5. Six Hypotheses about Colour recited (84, 85) Why the Author cannot more fully Speak of any of these (86.) nor Acquiesce in them (87, 88.) What Pyrophilus is to expect in this Treatise (88, 89.) What Hypothesis of Light and Colour the Author most inclines too (90.) Why he thinks neither that nor any other sufficient; and what his Difficulties are, that

make him decline all Hypotheses, and to think it very difficult to stick to any. (91, 92.)