Better Gutenberg
Free, beautifully formatted public-domain ebooks

Experiments and Considerations Touching Colours

by Robert Boyle

53 of 163 · Contents · Download EPUB

Experiment XXV

It may afford a considerable Hint (Pyrophilus) to him, that would improve the Art of Dying, to know what change of Colours may be produc’d by the three several sorts of Salts already often mention’d, (some or other of which may be procur’d in Quantity at reasonable Rates) in the Juices, Decoctions, Infusions, and (in a word) the more soluble parts of Vegetables. And, though the design of this Discourse be the Improvement of Knowledge, not of Trades: yet thus much I shall not scruple to intimate here, That the Blew Liquors, mention’d in the twentieth and one and twentieth Experiments, are far from being the only Vegetable Substances, upon which Acid, Urinous, and Alcalizate Salts have the like Operations to those recited in those two Experiments. For Ripe Privet Berries (for instance) being crush’d upon White Paper, though they stain it with a Purplish Colour, yet if we let fall on some part of it two or three drops of Spirit of Salt, and on the other part a little more of the Strong Solution of Pot-ashes, the former Liquor immediately turn’d that part of the Thick juice or Pulp, on which it fell, into a lovely Red, and the latter turn’d the other part of it into a delightfull Green. Though I will not undertake, that those Colours in that Substance shall not be much more Orient, than Lasting; and though (Pyrophilus) this Experiment may seem to be almost the same with those already deliver’d concerning Syrrup of Violets, and the Juice of Blew-bottles, yet I think it not amiss to take this Occasion to inform you, that this Experiment reaches much farther, than perhaps you yet imagine, and may be of good Use to those, whom it concerns to know, how Dying Stuffs may be wrought upon by Saline Liquors. For, I have found this Experiment to succeed in so many Various Berries, Flowers, Blossoms, and other finer Parts of Vegetables, that neither my Memory, nor my Leisure serves me to enumerate them. And it is somewhat surprizing to see, by how Differingly-colour’d Flowers, or Blossoms, (for example) the Paper being stain’d, will by an Acid Spirit be immediately turn’d Red, and by any Alcaly or any Urinous Spirit turn’d Green; insomuch that ev’n the crush’d Blossoms of Meserion, (which I gather’d in Winter and frosty Weather) and those of Pease, crush’d upon White Paper, how remote soever their Colours be from Green, would in a moment pass into a deep Degree of that Colour, upon the Touch of an Alcalizate Liquor. To which let us add, That either of those new Pigments (if I may so call them) may by the Affusion of enough of a contrary Liquor, be presently chang’d from Red into Green, and from Green into Red, which Observation will hold also in Syrrup of Violets, Juices of Blew-bottles, &c.

Annotation.

After what I have formerly deliver’d to evince, That there are many Instances, wherein new Colours are produc’d or acquir’d by Bodies, which Chymists are wont to think destitute of Salt, or to whose change of Colours no new Accession of Saline Particles does appear to contribute, I think we may safely enough acknowledge, that we have taken notice of so many Changes made by the Intervention of Salts in the Colours of Mix’d Bodies, that it has lessen’d our Wonder, That though many Chymists are wont to ascribe the Colours of Such Bodies to their Sulphureous, and the rest to their Mercurial Principle; yet Paracelsus himself directs us in the Indagation of Colours, to have an Eye principally upon Salts, as we find in that passage of his, wherein he takes upon him to Oblige his Readers much by Instructing them, of what things they are to expect the Knowledge from each of the three distinct Principles of Bodies. Alias (says he) Colorum similis ratio est: De quibus brevem institutionem hanc attendite, quod scilicet colores omnes ex Sale prodeant. Sal enim dat colorem, dat Balsamum.19 And a little beneath. Iam natura Ipsa colores protrathit ex sale, cuique speciei dans illum, qui ipsi competit, &c. After which he concludes; Itaque qui rerum omnium corpora cognoscere vult, huic opus est, ut ante omnia cognoscat Sulphur, Ab hoc, qui desiderat novisse Colores is scientiam istorum petat à Sale, Qui scire vult Virtutes, is scrutetur arcana Mercurii. Sic nimirum fundamentum hauserit Mysteriorum, in quolibet crescenti indagandorum, prout natura cuilibet speciei ea ingessit. But though Paracelsus ascribes to each of his belov’d Hypostatical Principles, much more than I fear will be found to belong to it; yet if we please to consider Colours, not as Philosophers, but as Dyers, the concurrence of Salts to the striking and change of Colours, and their Efficacy, will, I suppose, appear so considerable, that we shall not need to quarrel much with Paracelsus, for ascribing in this place (for I dare not affirm that he uses to be still of one Mind) the Colours of Bodies to their Salts, if by Salts he here understood, not only Elementary Salts, but such also as are commonly taken for Salts, as Allom, Crystals of Tartar, Vitriol, &c. because the Saline principle does chiefly abound in them, though indeed they be, as we elsewhere declare, mix’d Bodies, and have most of them, besides what is Saline, both Sulphureous, Aqueous, and Gross or Earthy parts.

But though (Pyrophilus) I have observ’d a Red and Green to be produc’d, the former, by Acid Salts, the later by Salts not Acid, in the express Juices of so many differing Vegetable Substances, that the Observation, if persued, may prove (as I said) of good Use: yet to show you how much e’vn these Effects depend upon the particular Texture of Bodies, I must subjoyn some cases wherein I (who am somewhat backwards to admit Observations for Universal) had the Curiosity to discover, that the Experiments would not Uniformly succeed, and of these Exceptions, the chief that I now remember, are reducible to the following three.

← Back to Experiments and Considerations Touching Colours

Scroll to Top