Chapter 16

I know not, _Pyrophilus_, whether it be worth while to acquaint you with the ways that came into my Thoughts, whereby in some measure to explicate the first of the mention'd ways of making a Green; for I have sometimes Conjectur'd, that the mixture of the Bise and the Orpiment produc'd a Green by so altering the Superficial Asperity, which each of those Ingredients had apart, that the Light Incident on the mixture was Reflected with differing Shades, as to Quantity, or Order, or both, from those of either of the Ingredients, and such as the Light is wont to be Modify'd with, when it Reflects from Grass, or Leaves, or some of those other Bodies that we are wont to call Green. And sometimes too I have doubted, whether the produced Green might not be partly at least deriv'd from this, That the Beams that Rebound from the Corpuscles of the Orpiment, giving one kind of stroak upon the _Retina_, whose Perception we call Yellow, and the Beams Reflected from the Corpuscles of the Bise, giving another stroak upon the same _Retina_, like to Objects that are Blew, the Contiguity and Minuteness of these Corpuscles may make the Appulse of the Reflected Light fall upon the _Retina_ within so narrow a Compass, that the part they Beat upon being but as it were a Physical point, they may give a Compounded stroak, which may consequently exhibit a Compounded and new Kind of Sensation, as we see that two Strings of a Musical Instrument being struck together, making two Noises that arrive at the Ear at the same time as to Sense, yield a Sound differing from either of them, and as it were Compounded of both; Insomuch that if they be Discordantly ton'd, though each of them struck apart would yield a Pleasing Sound, yet being struck together they make but a Harsh and troublesome Noise. But this not being so fit a place to prosecute Speculations, I shall not insist, neither upon these Conjectures nor any others, which the Experiment we have been mentioning may have suggested to me. And I shall leave it to you, _Pyrophilus_, to derive what Instruction you can from comparing together the Various ways whereby a Yellow and a Blew can be made to Compound a Green. That which I now pretend to, being only to shew that the first of those mention'd ways, (not to take at present notice of the rest) does far better agree with our Conjectures about Colours, than either with the Doctrine of the Schools, or with that of the _Chymists_, both which seem to be very much Disfavour'd by it.

For first, since in the Mixture of the two mention'd Powders I could by the help of a very excellent _Microscope_ (for ordinary ones will scarce serve the turn) discover that which seem'd to the naked Eye a Green Body, to be but a heap of Distinct, though very small Grains of Yellow Orpiment and Blew Bise confusedly enough Blended together, it appears that the Colour'd Corpuscles of either kind did each retain its own Nature and Colour; By which it may be guess'd, what meer Transposition and Juxtaposition of Minute and Singly unchang'd Particles of Matter can do to produce a new Colour; For that this Local Motion and new Disposition of the small parts of the Orpiment did Intervene is much more manifest than it is easie to Explicate how they should produce this new Green otherwise than by the new Manner of their being put together, and consequently by their new Disposition to Modifie the Incident Light by Reflecting it otherwise than they did before they were Mingl'd together.

Secondly, The Green thus made being (if I may so speak) Mechanically produc'd, there is no pretence to derive it from I know not what incomprehensible Substantial Form, from which yet many would have us believe that Colours must flow; Nor does this Green, though a Real and Permanent, not a Phantastical and Vanid Colour, seem to be such an Inherent Quality as they would have it, since not only each part of the Mixture remains unalter'd in Colour, and consequently of a differing Colour from the Heap they Compose, but if the Eye be assisted by a _Microscope_ to discern things better and more distinctly than before it could, it sees not a Green Body, but a Heap of Blew and Yellow Corpuscles.

And in the third place, I demand what either Sulphur, or Salt, or Mercury has to do in the Production of this Green; For neither the Bise nor the Orpiment were indu'd with that Colour before, and the bare Juxtaposition of the Corpuscles of the two Powders that work not upon each other, but might if we had convenient Instruments be separated, unalter'd, cannot with any probability be imagin'd either to Increase or Diminish any of the three Hypostatical Principles, (to which of them soever the _Chymists_ are pleas'd to ascribe Colours) nor does there here Intervene so much as Heat to afford them any colour to pretend, that at least there is made an Extraversion (as the _Helmontians_ speak) of the Sulphur or of any of the two other supposed Principles; But upon this Experiment we have already Reflected enough, if not more than enough for once.

_EXPERIMENT XVIII._

But here, _Pyrophilus_, I must advertise you, that 'tis not every Yellow and every Blew that being mingl'd will afford a Green; For in case one of the Ingredients do not Act only as endow'd with such a Colour, but as having a power to alter the Texture of the Corpuscles of the other, so as to Indispose them to Reflect the Light, as Corpuscles that exhibit a Blew or a Yellow are wont to Reflect it, the emergent Colour may be not Green, but such as the change of Texture in the Corpuscles of one or both of the Ingredients qualifies them to shew forth; as for instance, if you let fall a few Drops of Syrrup of Violets upon a piece of White Paper, though the Syrrup being spread will appear Blew, yet mingling with it two or three Drops of the lately mention'd Solution of Gold, I obtain'd not a Green but a Reddish mixture, which I expected from the remaining Power of the Acid Salts abounding in the Solution, such Salts or Saline Spirits being wont, as we shall see anon, though weakn'd, so to work upon that Syrrup as to change it into a Red or Reddish Colour. And to confirm that for which I allege the former Experiment, I shall add this other, that having made a very strong and high-colour'd Solution of Filings of Copper with Spirit of Urine, though the _Menstruum_ seem'd Glutted with the Metall, because I put in so much Filings that many of them remain'd for divers days Undissolv'd at the Bottom, yet having put three or four Drops of Syrrup of Violets upon White Paper, I found that the deep Blew Solution proportionably mingl'd with this other Blew Liquor did not make a Blew mixture, but, as I expected, a fair Green, upon the account of the Urinous Salt that was in the _Menstruum_.

_EXPERIMENT XIX._

To shew the _Chymists_, that Colours may be made to Appear or Vanish, where there intervenes no Accession or Change either of the Sulphureous, or the Saline, or the Mercurial principle (as they speak) of Bodies: I shall not make use of the Iris afforded by the Glass-prism, nor of the Colours to be seen in a fair Morning in those drops of Dew that do in a convenient manner Reflect and Refract the Beams of Light to the Eye; But I will rather mind them of what they may observe in their own Laboratories, namely, that divers, if not all, Chymical Essential Oyls, as also good Spirit of Wine, being shaken till they have good store of Bubbles, those Bubbles will (if attentively consider'd) appear adorn'd with various and lovely Colours, which all immediately Vanish, upon the relapsing of the Liquor that affords those Bubbles their Skins, into the rest of the Oyl, or Spirit of Wine, so that a Colourless Liquor may be made in a trice to exhibit variety of Colours, and may lose them in a moment without the Accession or Diminution of any of its Hypostatical Principles. And, by the way, 'tis not unworthy our notice, that some Bodies, as well Colourless, as Colour'd, by being brought to a great Thinness of parts, acquire Colours though they had none before, or Colours differing from them they were before endued with: For, not to insist on the Variety of Colours, that Water, made somewhat Glutinous by Sope, acquires, when 'tis blown into such Sphærical Bubbles as Boys are wont to make and play with; Turpentine (though it have a Colour deep enough of its own) may (by being blown into after a certain manner) be brought to afford Bubbles adorn'd with variety of Orient Colours, which though they Vanish after some while upon the breaking of the Bubbles, yet they would in likelihood always exhibit Colours upon their _Superfices_, (though not always the same in the same Parts of them, but Vary'd according to the Incidence of the Sight, and the Position of the Eye) if their Texture were durable enough: For I have seen one that was Skill'd at fashioning Glasses by the help of a Lamp, blowing some of them so strongly as to burst them, whereupon it was found, that the Tenacity of the Metall was such, that before it broke it suffer'd it self to be reduc'd into Films so extremely thin, that being kept clean they constantly shew'd on their Surfaces (but after the manner newly mention'd) the varying Colours of the Rain-bow, which were exceedingly Vivid, as I had often opportunity to observe in some, that I caus'd purposely to be made, to keep by me.

But lest it should be objected, that the above mentioned Instances are drawn from Transparent Liquors, it may possibly appear, not impertinent to add, what I have sometimes thought upon, and several times tried, when I was considering the Opinions of the _Chymists_ about Colours, I took then a Feather of a convenient Bigness and Shape, and holding it at a fit distance betwixt my Eye and the Sun when he was near the Horizon, me thought there appear'd to me a Variety of little Rain-bows, with differing and very vivid Colours, of which none was constantly to be seen in the Feather; the like _Phænomenon_ I have at other times (though not with altogether so good success) produc'd, by interposing at a due distance a piece of Black Ribband betwixt the almost setting Sun and my Eye, not to mention the Trials I have made to the same purpose, with other Bodies.

_EXPERIMENT XX._

Take good Syrrup of Violets, Imprægnated with the Tincture of the flowers, drop a little of it upon a White Paper (for by that means the Change of Colour will be more conspicuous, and the Experiment may be practis'd in smaller Quantities) and on this Liquor let fall two or three drops of Spirit either of Salt or Vinegar, or almost any other eminently Acid Liquor, and upon the Mixture of these you shall find the Syrrup immediatly turn'd Red, and the way of Effecting such a Change has not been unknown to divers Persons who have produc'd the like, by Spirit of Vitriol, or juice of Limmons, but have Groundlessly ascrib'd the Effect to some Peculiar Quality of those two Liquors, whereas, (as we have already intimated) almost any Acid Salt will turn Syrrup of Violets Red. But to improve the Experiment, let me add what has not (that I know of) been hitherto observ'd, and has, when we first shew'd it them, appear'd something strange, even to those that have been inquisitive into the Nature of Colours; namely, that if instead of Spirit of Salt, or that of Vinegar, you drop upon the Syrrup of Violets a little Oyl of Tartar _per Deliquium_, or the like quantity of Solution of Potashes, and rubb them together with your finger, you shall find the Blew Colour of the Syrrup turn'd in a moment into a perfect Green, and the like may be perform'd by divers other Liquors, as we may have occasion elsewhere to Inform you.

_Annotation upon the twentieth Experiment_.

The use of what we lately deliver'd concerning the way of turning Syrrup of Violets, Red or Green, may be this; That, though it be a far more common and procurable Liquor than the Infusion of _Lignum Nephriticum_, it may yet be easily substituted in its Room, when we have a mind to examine, whether or no the Salt predominant in a Liquor or other Body, wherein 'tis Loose and Abundant, belong to the Tribe of _Acid_ Salts or not. For if such a Body turn the Syrrup of a Red or Reddish Purple Colour, it does for the most part argue the Body (especially if it be a distill'd Liquor) to abound with Acid Salt. But if the Syrrup be made Green, that argues the Predominant Salt to be of a Nature repugnant to that of the Tribe of Acids. For, as I find that either Spirit of Salt, or Oyl of Vitriol, or _Aqua-fortis_, or Spirit of Vinegar, or Juice of Lemmons, or any of the Acid Liquors I have yet had occasion to try, will turn Syrrup of Violets, of a _Red_, (or at least, of a _Reddish_ Colour, so I have found, that not only the Volatile Salts of all Animal Substances I have us'd, as Spirit of Harts-horn, of Urine, of Sal-Armoniack, of Blood, &c. but also all the Alcalizate Salts I have imploy'd, as the Solution of Salt of Tartar, of Pot-ashes, of common Wood-ashes, Lime-water, &c. will immediately change the Blew Syrrup, into a perfect Green. And by the same way (to hint that upon the by) I elsewhere show you, both the changes that Nature and Time produce, in the more Saline parts of some Bodies, may be discover'd, and also how ev'n such Chymically prepar'd Bodies, as belong not either to the Animal Kingdome, or to the Tribe of _Alcali's_, may have their new and superinduc'd Nature successfully Examin'd. In this place I shall only add, that not alone the Changing the Colour of the Syrrup, requires, that the Changing Body be more strong, of the Acid, or other sort of Salt that is Predominant in it, than is requisite for the working upon the Tincture of _Lignum Nephriticum_; but that in this is also, the Operation of the formerly mention'd Salts upon our Syrrup, differs from their Operation upon our Tinctures, that in this Liquor, if the Cæruleous Colour be _Destroy'd_ by an Acid Salt, it may be _Restor'd_ by one that is either Volatile, or Lixiviate; whereas in Syrrup of Violets, though one of these contrary Salts will _destroy_ the Action of the other, yet neither of them will _restore_ the Syrrup to its native Blew; but each of them will Change it into the Colour which it self doth (if I may so speak) affect, as we shall have Occasion to show in the Notes on the twenty fifth Experiment.

_EXPERIMENT XXI._

There is a Weed, more known to Plowmen than belov'd by them, whose Flowers from their Colour are commonly call'd _Blew-bottles_, and _Corn-weed_ from their Growing among Corn[18]. These Flowers some Ladies do, upon the account of their Lovely Colour, think worth the being Candied, which when they are, they will long retain so fair a Colour, as makes them a very fine Sallad in the Winter. But I have try'd, that when they are freshly gather'd, they will afford a Juice, which when newly express'd, (for in some cases 'twill soon enough degenerate) affords a very deep and pleasant Blew. Now, (to draw this to our present Scope) by dropping on this fresh Juice, a little Spirit of Salt, (that being the Acid Spirit I had then at hand) it immediately turn'd (as I predicted) into a Red. And if instead of the Sowr Spirit I mingled with it a little strong Solution of an Alcalizate Salt, it did presently disclose a lovely Green; the same Changes being by those differing sorts of Saline Liquors, producible in this _Natural juice_, that we lately mention'd to have happen'd to that _factitious Mixture_, the Syrrup of Violets. And I remember, that finding this Blew Liquor, when freshly made, to be capable of serving in a Pen for an Ink of that Colour, I attempted by moistning one part of a piece of White Paper with the Spirit of Salt I have been mentioning, and another with some Alcalizate or Volatile Liquor, to draw a Line on the leisurely dry'd Paper, that should, e'vn before the Ink was dry, appear partly Blew, partly Red, and partly Green: But though the latter part of the Experiment succeeded not well, (whether because Volatile Salts are too Fugitive to be retain'd in the Paper, and Alcalizate ones are too Unctuous, or so apt to draw Moisture from the Air, that they keep the Paper from drying well) yet the former Part succeeded well enough; the Blew and Red being Conspicuous enough to afford a surprizing Spectacle to those, I acquaint not with (what I willingly allow you to call) the _Trick_.

[18] _Herbarists_ are wont to call this Plant _Cyanus vulgaris minor_.

_Annotation upon the one and twentieth Experiment._

But lest you should be tempted to think (_Pyrophilus_) that Volatile or Alcalizate Salts change Blews into Green, rather upon the score of the easie Transition of the former Colour into the latter, than upon the account of the Texture, wherein most Vegetables, that afford a Blew, seem, though otherwise differing, to be Allied, I will add, that when I purposely dissolv'd Blew Vitriol in fair Water, and thereby imbu'd sufficiently that Liquor with that Colour, a Lixiviate Liquor, and a Urinous Salt being Copiously pour'd upon distinct Parcels of it, did each of them, though perhaps with some Difference, turn the Liquor not Green, but of a deep Yellowish Colour, almost like that of Yellow Oker, which Colour the Precipitated Corpuscles retain'd, when they had Leisurely subsided to the Bottom. What this Precipitated Substance is, it is not needfull now to Enquire in this place, and in another, I have shown you, that notwithstanding its Colour, and its being Obtainable from an Acid _Menstruum_ by the help of Salt of Tartar, it is yet far enough from being the true Sulphur of Vitriol.

_EXPERIMENT XXII._

Our next Experiment (_Pyrophilus_) will perhaps seem to be of a contrary Nature to the two former, made upon Syrrup of Violets, and Juice of Blew-bottles. For as in them by the Affusion of Oyl of Tartar, a Blewish Liquor is made Green, so in this, by the sole Mixture of the same Oyl, a Greenish Liquor becomes Blew. The hint of this Experiment was given us by the practice of some _Italian_ Painters, who being wont to Counterfeit _Ultra-marine Azure_ (as they call it) by Grinding Verdigrease with Sal-Armoniack, and some other Saline Ingredients, and letting them Rot (as they imagine) for a good while together in a Dunghill, we suppos'd, that the change of Colour wrought in the Verdigrease by this way of Preparation, must proceed from the Action of certain Volatile and Alcalizate Salts, abounding in some of the mingled Concretes, and brought to make a further Dissolution of the Copper abounding in the Verdigrease, and therefore we Conjectur'd, that if both the Verdigrease, and such Salts were dissolv'd in fair Water, the small Parts of both being therein more subdivided, and set at liberty, would have better access to each other, and thereby Incorporate much the more suddenly; And accordingly we found, that if upon a strong Solution of good French Verdigrease (for 'tis that we are wont to imploy, as the best) you pour a just quantity of Oyl of Tartar, and shake them well together, you shall immediately see a notable Change of Colour, and the Mixture will grow thick, and not transparent, but if you stay a while, till the Grosser part be Precipitated to, and setled in the Bottom, you may obtain a clear Liquor of a very lovely Colour, and exceeding delightfull to the Eye. But, you must have a care to drop in a competent Quantity of Oyl of Tartar, for else the Colour will not be so Deep, and Rich; and if instead of this Oyl you imploy a clear _Lixivium_ of Pot-ashes, you may have an Azure somewhat Lighter or Paler than, and therefore differing from, the former. And if instead of either of these Liquors, you make use of Spirit of Urine, or of Harts-horn, you may according to the Quantity and Quality of the Spirit you pour in, obtain some further Variety (though scarce considerable) of Cæruleous Liquors. And yet lately by the help of this Urinous Spirit we made a Blew Liquor, which not a few Ingenious Persons, and among them, some, whose Profession makes them very Conversant with Colours, have looked upon with some wonder. But these Azure Colour'd Liquors should be freed from the Subsiding matter, which the Salts of Tartar or Urine precipitate out of them, rather by being Decanted, than by Filtration. For by the latter of these ways we have sometimes found, the Colour of them very much Impair'd, and little Superiour to that of the grosser Substance, that it left in the Filtre.

_EXPERIMENT XXIII._

That Roses held over the Fume of Sulphur, may quickly by it be depriv'd of their Colour, and have as much of their Leaves, as the Fume works upon, burn'd pale, is an Experiment, that divers others have tried, as well as I. But (_Pyrophilus_) it may seem somewhat strange to one that has never consider'd the Compounded nature of Brimstone, That, whereas the Fume of Sulphur will, as we have said, Whiten the Leaves of Roses; That Liquor, which is commonly call'd Oyl of Sulphur _per Campanam_, because it is suppos'd to be made by the Condensation of these Fumes in Glasses shap't like Bells, into a Liquor, does powerfully heighten the Tincture of Red Roses, and make it more Red and Vivid, as we have easily tried by putting some Red-Rose Leaves, that had been long dried, (and so had lost much of their Colour) into a Vial of fair Water. For a while after the Affusion of a convenient Quantity of the Liquor we are speaking of, both the Leaves themselves, and the Water they were Steep'd in, discover'd a very fresh and lovely Colour.

_EXPERIMENT XXIV._

It may (_Pyrophilus_) somewhat serve to Illustrate, not only the Doctrine of _Pigments_, and of _Colours_, but divers other Parts of the _Corpuscular Philosophy_; as that explicates Odours, and many other things, not as the Schools by Aery Qualities, but by Real, though extremely Minute Bodies; to examine, how much of a Colourless Liquor, a very small Parcel of a Pigment may Imbue with a _discernable_ Colour. And though there be scarce any thing of Preciseness to be expected from such Trials, yet I presum'd, that (at least) I should be able to show a much further Subdivision of the Parts of Matter into _Visible_ Particles, than I have hitherto found taken notice of, and than most men would imagine; no Body, that I know of, having yet attempted to reduce this Matter to any Measure.

The Bodies, the most promising for such a purpose, might seem to be the Metalls, especially Gold, because of the Multitude, and Minuteness of its Parts, which might be argu'd from the incomparable Closeness of its Texture: But though we tried a Solution of Gold made in _Aqua Regia_ first, and then in fair Water; yet in regard we were to determine the Pigment we imploy'd, not by _Bulk_ but _Weight_, and because also, that the Yellow Colour of Gold is but a faint one in Comparison of the deep Colour of _Cochineel_, we rather chose this to make our Trials with. But among divers of these it will suffice to set down one, which was carefully made in Vessels conveniently Shap'd; (and that in the presence of a Witness, and an Assistant) the Sum whereof I find among my _Adversaria_, Registred in the following Words. To which I shall only premise, (to lessen the wonder of so strange a diffusion of the Pigment) That _Cochineel_ will be better Dissolv'd, and have its Colour far more heightn'd by Spirit of Urine, than (I say not by common Water, but) by Rectify'd Spirit of Wine it self.

The Note I spoke off is this. [One Grain of _Cochineel_ dissolv'd in a pretty Quantity of Spirit of Urine, and then dissolv'd further by degrees in fair Water, imparted a discernable, though but a very faint Colour, to about six Glass-fulls of Water, each of them containing about forty three Ounces and an half, which amounts to above a hundred twenty five thousand times its own Weight.]

_EXPERIMENT XXV._