Boyle's Color Experiments - With Contemporary Provenance

Boyle, Robert (1627-91)

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, Fellow of the Royal Society

London: printed for Henry Herringman at the Anchor in the Lower Walk of the New Exchange, 1664


Octavo: 16.5 x 10.5 cm. [40], 423, [1] p., With 1 folding plate. Collation: A8, a8, b4, B-Z8, Aa-Dd8, Ee4


Bound in contemporary blind-ruled calfskin, rebacked. A fine copy internally. Plate a bit soiled, strenghtened on verso. "A short account of some observations made by Mr. Boyle about a diamond that shines in the dark" has separate dated title page; pagination and register are continuous. The plate illustrates one of Boyle's color experiments using a prism.

PROVENANCE: Thomas Gay of Trinity College, Oxford, ownership inscription dated 1689 on fly-leaf; Robert Gay (c.1676–1738), surgeon of London, ownership inscription dated 1695 on title, and full page of chemical annotations relating to colors and alkalis on the front free endpaper. (It was Boyle who, in 1663 discovered that acids would change the color of a vegetable dye called litmus. When extracted, this dye is blue in color, but when acid is added, the dye turns red. This was the first, easy assay, or test, for acids.)

"Robert Boyle (1627–1691) was perhaps the most famous natural philosopher of his day: he was one of the most forceful advocates of the mechanical philosophy as well as the experimental philosophy, which together were the foundations of the dominant ideological intellectual program in the second half of the seventeenth century.

"In his Experiments and Considerations Touching Colours, first published in 1664, Boyle’s stated purpose is to provide experiments and observations that “enquire seriously into the Nature of Colours, and assist in the Investigation of it.” While Boyle says to his readers that experiments on colors can offer pleasant diversions, he is primarily interested in accomplishing two things: establishing matters of fact throughout his treatise, and supplanting an Aristotelian theory of qualities with a mechanical or corpuscular one.

"There are two reasons why Touching Colours is regarded as a pre-eminent work in the history of science: it was here that Boyle first described color indicators for acids and bases; moreover, this text had significant influence on the young Isaac Newton’s investigations (the book includes Boyle's own experiments with prisms.) Touching Colours is also of great interest for the history and philosophy of experiment.

It is also in Touching Colours that Boyle introduced the term (though not the concept of) "primary colors" for the first time:

"There are but few Simple and Primary Colours (if I may so call them) from whose Various Compositions all the rest do as it were Result. For though Painters can imitate the Hues (though not always the Splendor) of those almost Numberless differing Colours that are to be met with in the Works of Nature, and of Art, I have not yet found, that to exhibit this strange Variety they need imploy any more than White, and Black, and Red, and Blew, and Yellow; these five, Variously Compounded, and (if I may so speak) Decompounded (i.e. twice compounded), being sufficient to exhibit a Variety and Number of Colours, such, as those that are altogether Strangers to the Painters Pallets, can hardly imagine.


"Thus (for Instance) Black and White differingly mix’d, make a Vast company of Lighter and Darker Grays. Blew and Yellow make a huge Variety of Greens. Red and Yellow make Orange Tawny. Red with a little White makes a Carnation. Red with an Eye of Blew, makes a Purple; and by these simple Compositions again Compounded among themselves, the Skilfull Painter can produce what kind of Colour he pleases, and a great many more than we have yet Names for."

"Boyle adds, however, that painters cannot always reproduce every degree of splendor. The mixing of pigments is merely mechanical (i.e., according to juxtaposition) and not chymical, and thus for him the scheme of the painters primaries only applies when the color-relevant textures of the particles of the various pigments are not altered via chymical interaction. This is significant and rather curious: here Boyle uses terms that were originally formed at the intersection of philosophy, alchemy and natural magic to describe true chemical mixture, but he applies these terms to an understanding of the phenomenal colors that result from pigment combinations, or what we would now call optical color mixture.

"According to Boyle, this is not the only way to generate new colors. As seen in the workshop, in the chymist’s laboratory and in plant and animal bodies, chymical mixture also generates new colors via compounding and decompounding of actual particles to produce new ingredients, and not just juxtapositions of colored parts. Colors produced by this chymical mixture do not obey the same laws as optical color mixture. Distinguishing between the color that results from the mere juxtaposition of tiny colored corpuscles on the one hand and chemical combinations that produce new colors on the other is highly significant for the question of whether color is either a superficial accident or else a sign of more ‘inward’ properties. How, according to Boyle, are we to distinguish between the two, and, more generally, how can we discover the true significance of the color of a body?

"While Touching Colours was first published in 1664, Boyle says it was originally written “by snatches, at several times, and places.” Boyle’s stated purpose for his experimental history in Touching Colours is to provide an “Apparatus to a sound and comprehensive Hypothesis,” but one that he intends his readers, rather than himself, to develop. He claims that he will refrain from forming or supposing a full theory of colors, only noting that any comprehensive theory should be constrained by the notion that “Beams of Light, Modify’d by the Bodies whence they are sent (reflected or refracted) to the Eye, produce there that Kind of Sensation, Men commonly call Colour.”

"Boyle writes at length on the question of whether ‘emphatical’ or ‘apparent’ colors are ‘true’ or ‘genuine’ colors. His discussion draws much from earlier mechanical philosophers such as Descartes, although Boyle’s discussion is longer (and arguably more nuanced) than Descartes’.

"As examples of apparent colors, Boyle includes the colors of the rainbow, colors from prisms, and peacock feathers – all classic topoi in writings about color. Early in the treatise he writes:

'for Colour may be considered, either as it is a quality residing in the body that is said to be coloured, or to modifie the light after such or such a manner; or else as the Light it self, which so modifi’d, strikes upon the organ of sight, and so causes that Sensation which we call Colour; and that this latter may be look’d upon as the more proper, though not the usual acception of the word Colour, will be made probable by divers passages in the insuing part of our discourse; and indeed it is the Light it self, which after a certain manner, either mingled with shades, or some other waies troubled, strikes our eyes, that does more immediately produce that motion in the organ, upon whose account men say they see such or such a Colour in the object.'

"Boyle explains this in greater detail later in the treatise, where his opinion is that, because color is in truth a property of light rather than the surface of a body, “Colours, or at least divers of them, are but Diversified Light, and not such Real and Inherent qualities as they are commonly thought to be.” What makes sensible qualities true and genuine rather than imaginary is that “they are the proper objects of some or other of our Senses.” Here, at least, Boyle’s stance is that colors are appearances caused by light reaching our eyes. All colors are real because our sensations of color are, in every case, caused by modified light."(Tawrin Baker, Color and Contingency in Robert Boyle’s Works, in Early Science and Medicine, Vol. 20, issue 4-6, p. 536-561)

Boyle's Prism Experiments:

The plate in Touching Colours illustrates one of Boyle's four prism experiments. "Boyle reported four experiments using prisms. Two of these involved the production of as many as four sets of emphatical colors, or 'irises', as Boyle called them, from rays of sunlight falling upon an equilateral crystal prism in a darkened room. In another pair of trials, Boyle sought to sustain the view that there was no difference between real and emphatic colors by casting the prismatic iris upon a 'really' colored object. He sought to show that emphatic colors combined with real ones just as real colors did with each other. Prismatic blue shone on red cloth made it seem purple. Attempts to use prisms tinted with real colors were very troubled, because the tints rendered the glass rather opaque. However, despite these difficulties, and the limited use Boyle made of his instrument, he emphasized the prism's status: it was 'the usefullest Instrument Men have yet employed about the Contemplation of Colours' and 'the Instrument upon whose Effects we may the most Commodiously speculate the Nature of Emphatical Colours, (and perhaps that of Others too).' Newton soon took up this suggestion, so changing the place of the prism in experimental optics."

Fulton 57; ESTC R19422; Wing (2nd ed., 1994), B3967