Experiment L.
Yet here, Pyrophilus, I muſt take leave to inſert an Experiment, though perhaps you’l think its coming in here an Intruſion, For I confeſs its more proper place would have been among thoſe Experiments, that were brought as proofs and applications of our Notions concerning the differences of Salts; but not having remembred to inſert it in its fitteſt place, I had rather take notice of it in this, than leave it quite unmention’d: partly becauſe it doth ſomewhat differ from the reſt of our Experiments about Colours, in the way whereby ’tis made; and partly becauſe the grounds upon which I devis’d it, may hint to you ſomewhat of the Method I uſe in Deſigning and Varying Experiments about Colours, and upon this account I ſhall inform you, not only What I did, but Why I did it.
I conſider’d then that the work of the former Experiments was either to change the Colour of a Body into another, or quite to deſtroy it, without giving it a ſucceſſor, but I had a mind to give you alſo a way, whereby to turn a Body endued with one Colour into two Bodies, of Colours, as well as conſiſtencies, very diſtinct from each other, and that by the help of a Body that had it ſelf no Colour at all. In order to this, I remembred, that finding the Acidity of Spirit of Vinegar to be wholly deſtroy’d by its working upon Minium (or calcin’d Lead) whereby the Saline particles of the Menſtruum have their Taſte and Nature quite alter’d, I had, among other Conjectures I had built upon that change, rightly concluded, that the Solution of Lead in Spirit of Vinegar would alter the Colour of the Juices and Infuſions of Several Plants, much after the like manner that I had found Oyl of Tartar to do; and accordingly I was quickly ſatisfied upon Tryal, that the Infuſion of Roſe-leaves would by a ſmall quantity of this Solution well mingl’d with it, be immediately turn’d into a ſomewhat ſad Green.
And further, I had often found, that Oyl of Vitriol, though a potently Acid Menſtruum, will yet Præcipitate many Bodies, both Mineral and others, diſſolv’d not onely in Aqua fortis (as ſome Chymiſts have obſerv’d) but particularly in Spirit of Vinegar, and I have further found, that the Calces or Powders Præcipitated by this Liquor were uſually fair and White.
Laying theſe things together, ’twas not difficult to conclude, that if upon a good Tincture of Red Roſe-leaves made with fair Water, I dropp’d a pretty quantity of a ſtrong and ſweet Solution of Minium, the Liquor would be turn’d into the like muddy Green Subſtance, as I have formerly intimated to You, that Oyl of Tartar would reduce it to, and that if then I added a convenient quantity of good Oyl of Vitriol, this laſt nam’d Liquor would have two diſtinct operations upon the Mixture, the one, that it would Præcipitate that reſolv’d Lead in the form of a White Powder; the other, that it would Clarifie the muddy Mixture, and both reſtore, and exceedingly heighten the Redneſs of the Infuſion of Roſes, which was the moſt copious Ingredient of the Green compoſition, and accordingly trying the Experiment in a Wine glaſs ſharp at the bottom (like an inverted Cone) that the ſubſiding Powder might ſeem to take up the more room, and be the more conſpicuous, I found that when I had ſhaken the Green Mixture, that the colour’d Liquor might be the more equally diſperſed, a few drops of the rectifi’d Oyl of Vitriol did preſently turn the opacous Liquor into one that was cleer and Red, almoſt like a Rubie, and threw down good ſtore of a Powder, which when ’twas ſettl’d, would have appear’d very White, if ſome interſpers’d Particles of the red Liquor had not a little Allay’d the Purity, though not blemiſh’d the Beauty of the Colour. And to ſhew you, Pyrophilus, that theſe Effects do not flow from the Oyl of Vitriol, as it is ſuch, but as it is a ſtrongly Acid Menſtruum, that has the property both to Præcipitate Lead, as well as ſome other Concretes out of Spirit of Vinegar, and to heighten the Colour of Red Roſe-leaves, I add, that I have done the ſame thing, though perhaps not quite ſo well with Spirit of Salt, and that I could not do it with Aqua-fortis, becauſe though that potent Menſtruum does as well as the others heighthen the Redneſs of Roſes, yet it would not like them Precipitate Lead out of Spirit of Vinegar, but would rather have diſſolv’d it, if it had not found it diſſolv’d already.
And as by this way we have produc’d a Red Liquor, and a White Precipitate out of a Dirty Green magiſtery of Roſe-leaves, ſo by the ſame Method, you may produce a fair Yellow, and ſometimes a Red Liquor, and the like Precipitate, out of an Infuſion of a curious Purple Colour. For you may call to mind, that in the Annotation upon the 39th. Experiment I intimated to you, that I had with a few drops of an Alcaly turn’d the Infuſion of Logg-wood into a lovely Purple. Now if inſtead of this Alcaly I ſubſtituted a very Strong and well Filtrated Solution of Minium, made with Spirit of Vinegar, and put about half as much of this Liquor as there was of the Infuſion of Logg-wood, (that the mixture might afford a pretty deal of Precipitate,) the affuſion of a convenient proportion of Spirit of Salt, would (if the Liquors were well and nimbly ſtirr’d together) preſently ſtrike down a Precipitate like that formerly mention’d, and turn the Liquor that ſwam above it, for the moſt part into a lovely Yellow.
But for the advancing of this Experiment a little further, I conſider’d, that in caſe I firſt turn’d a ſpoonfull of the infuſion of Logg-wood Purple, by a convenient proportion of the Solution of Minium, the Affuſion of Spirit of Sal Armnoniack, would Precipitate the Corpuſcles of Lead conceal’d in the Solution of Minium, and yet not deſtroy the Purple colour of the Liquor; whereupon I thus proceeded; I took about a ſpoonfull of the freſh Tincture of Logg-wood, (for I found that if it were ſtale the Experiment would not alwayes ſucceed,) and having put to it a convenient proportion of the Solution of Minium to turn it into a deep and almoſt opacous Purple, I then drop’d in as much Spirit of Sal Armoniack, as I gueſs’d would Precipitate about half or more (but not all) of the Lead, and immediately ſtirring the mixture well together, I mingled the Precipitated parts with the others, ſo that they fell to the bottom, partly in the form of a Powder, and partly in the form of a Curdled Subſtance, that (by reaſon of the Predominancy of the Ting’d Corpuſcles over the White) retain’d as well as the Supernatant Liquor; a Blewiſh Purple colour ſufficiently Deep, and then inſtantly (but yet Warily,) pouring on a pretty Quantity of Spirit of Salt, the matter firſt Precipitated, was, by the above ſpecified figure of the bottome of the Glaſs preſerv’d from being reach’d by the Spirituous Salt; which haſtily Precipitated upon it a new Bed (if I may ſo call it) of White Powder, being the remaining Corpuſcles of the Lead, that the Urinous Spirit had not ſtruck down: So that there appear’d in the Glaſs three diſtinct and very differingly colour’d Subſtances; a Purple or Violet-colour’d Precipitate at the bottom, a White and Carnation (ſometimes a Variouſly colour’d) Precipitate over That, and at the Top of all a Tranſparent Liquor of a lovely Yellow, or Red.
Thus you ſee, Pyrophilus, that though to ſome I may have ſeem’d to have lighted on this (50th.) Experiment by chance, and though others may imagine, that to have excogitated it, muſt have proceeded from ſome extraordinary inſight into the nature of Colours, yet indeed, the deviſing of it need not be look’d upon as any great matter, eſpecially to one that is a little vers’d in the notions, I have in theſe, and other Papers hinted concerning the differences of Salts. And perhaps I might add upon more than conjecture, that theſe very notions and ſome particulars ſcatteringly deliver’d in this Treatiſe, being skilfully put together, may ſuggeſt divers matters (at leaſt,) about Colours, that will not be altogether Deſpicable. But thoſe hinted, Pyrophilus, I muſt now leave ſuch as You to proſecute, having already ſpent farr more time than I intended to allow my ſelf in acquainting You with particular Experiments and Obſervations concerning the changes of Colour, to which I might have added many more, but that I hope I may have preſented You with a competent number to make out in ſome meaſure what I have at the beginning of this Eſſay either propos’d as my Deſign in this Tract, or deliver’d as my Conjectures concerning theſe matters. And it not being my preſent Deſigne, as I have more than once Declar’d, to deliver any Poſitive Hypotheſis or ſolemn Theory of Colours, but only to furniſh You with ſome Experiments towards the framing of ſuch a Theory; I ſhall add nothing to what I have ſaid already, but a requeſt that you would not be forward to think I have been miſtaken in any thing I have deliver’d as matter of Fact concerning the changes of Colours, in caſe you ſhould not every time you trye it, find it exactly to ſucceed. For beſides the Contingencies to which we have elſewhere ſhewn ſome other Experiments to be obnoxious, the omiſſion or variation of a ſeemingly unconſiderable circumſtance, may hinder the ſucceſs of an Experiment, wherein no other fault has been committed. Of which truth I ſhall only give you that ſingle and almoſt obvious, but yet illuſtrious inſtance of the Art of Dying Scarlets, for though you ſhould ſee every Ingredient that is us’d about it, though I ſhould particularly inform You of the weight of each, and though you ſhould be preſent at the kindling of the fire, and at the increaſing and remitting of it, when ever the degree of Heat is to be alter’d, and though (in a word) you ſhould ſee every thing done ſo particularly that you would ſcarce harbour the leaſt doubt of your comprehending the whole Art: Yet if I ſhould not diſcloſe to You, that the Veſſels, that immediately contain the Tinging Ingredients, are to be made of or to be lin’d with Tin, You would never be able by all that I could tell you elſe (at-leaſt, if the Famouſeſt and Candideſt Artificers do not ſtrangely delude themſelves) to bring your Tincture of Chochinele to Dye a perfect Scarlet. So much depends upon the very Veſſel, wherein the Tinging matters are boyl’d, and ſo great an Influence may an unheeded Circumſtance have on the Succeſs of Experiments concerning Colours.