EXPERIMENT XLVI.
We have often taken notice, as of a remarkable thing, that Metalls as they appear to the Eye, before they come to be farther alter'd by other Bodyes, do exhibit Colours very different from thoſe which the Fire and the Menſtruum, either apart, or both together, do produce in them; eſpecially conſidering that theſe Metalline Bodyes are after all theſe diſguiſes reducible not only to their former Metalline Conſiſtence and other more radical properties, but to their Colour too, as if Nature had given divers Metalls to each of them a double Colour, an External, and an Internal; But though upon a more attentive Conſideration of this difference of Colours, it ſeem'd probable to me, that divers (for I ſay not all) of thoſe Colours which we have juſt now call'd Internal, are rather produc'd by the Coalition of Metalline Particles with thoſe of the Salts, or other Bodyes employ'd to work on them, than by the bare alteration of the parts of the Metalls themſelves: and though therefore we may call the obvious Colours, Natural or Common, & the others Adventitious, yet becauſe ſuch changes of Colours, from whatſoever cauſe they be reſolv'd to proceed may be properly enough taken in to illuſtrate our preſent Subject, we ſhall not ſcruple to take notice of ſome of them, eſpecially becauſe there are among them ſuch as are produc'd without the intervention of Saline Menſtruums. Of the Adventitious Colours of Metalline Bodies the Chief ſorts ſeem to be theſe three. The firſt, ſuch Colours as are produc'd without other Additaments by the Action of the fire upon Metalls. The next ſuch as emerge from the Coalition of Metalline Particles with thoſe of ſome Menstruum imploy'd to Corrode a Metall or Precipitate it; And the laſt, The Colours afforded by Metalline Bodyes either Colliquated with, or otherwiſe Penetrating into, other Bodies, eſpecially fuſible ones. But theſe (Pyrophilus,) are only as I told you, the Chief ſorts of the adventitious Colours of Metalls, for there may others belong to them, of which I ſhall hereafter have occaſion to take notice of ſome, and of which alſo there poſſibly may be others that I never took notice of.
And to begin with the firſt ſort of Colours, 'tis well enough known to Chymiſts, that Tin being Calcin'd by fire alone is wont to afford a White Calx, and Lead Calcin'd by fire alone affords that moſt Common Red-Powder we call Minium: Copper alſo Calcin'd per ſe, by a long or violent fire, is wont to yield (as far as I have had occaſion to take notice of it) a very Dark or Blackiſh Powder; That Iron likewiſe may by the Action of Reverberated flames be turn'd into a Colour almoſt like that of Saffron, may be eaſily deduc'd from the Preparation of that Powder, which by reaſon of its Colour and of the Metall 'tis made of is by Chymiſts call'd, Crocus Martis per ſe. And that Mercury made by the ſtreſs of Fire, may be turn'd into a Red Powder, which Chymiſts call Precipitate per ſe, I elſewhere more particularly declare.
Annotation I.
It is not unworthy the Admoniſhing you, (Pyrophilus,) and it agrees very well with our Conjectures about the dependence of the change of a Body's Colour upon that of its Texture, that the ſame Metall may by the ſucceſſive operation of the fire receive divers Adventitious Colours, as is evident in Lead, which before it come to ſo deep a Colour as that of Minium, may paſs through divers others.
Annotation II.
Not only the Calces, but the Glaſſes of Metalls, Vitrify'd per ſe, may be of Colours differing from the Natural or Obvious Colour of the Metall; as I have obſerv'd in the Glaſs of Lead, made by long expoſing Crude Lead to a violent fire, and what I have obſerv'd about the Glaſs or Slagg of Copper, (of which I can ſhow you ſome of an odd kind of Texture,) may be elſewhere more conveniently related. I have likewiſe ſeen a piece of very Dark Glaſs, which an Ingenious Artificer that ſhow'd it me profeſs'd himſelf to have made of Silver alone by an extreme Violence (which ſeems to be no more than is needfull) of the fire.
Annotation III.
Minerals alſo by the Action of the Fire may be brought to afford Colours very differing from their own, as I not long ſince noted to you about the variouſly Colour'd Flowers of Antimony, to which we may add the Whitiſh Grey-Colour of its Calx, and the Yellow or Reddiſh Colour of the Glaſs, where into that Calx may be flux'd.
And I remember, that I elſewhere told you, that Vitriol Calcin'd with a very gentle heat, and afterwards with higher and higher degrees of it, may be made to paſs through ſeveral Colours before it deſcends to a Dark Purpliſh Colour, whereto a ſtrong fire is wont at length to reduce it. But to inſiſt on the Colours produc'd by the Operation of fire upon ſeveral Minerals would take up farr more time than I have now to ſpare.
EXPERIMENT XLVII.
The Adventitious Colours produc'd upon Metalls, or rather with them, by Saline Liquors, are many of them ſo well known to Chymiſts, that I would not here mention them, but that beſides a not un-needed Teſtimony, I can add ſomething of my own, to what I ſhall repeat about them, and divers Experiments which are familiar to Chymiſts, are as yet unknown to the greateſt part of Ingenious Men.
That Gold diſſolv'd in Aqua Regia ennobles the Menſtruum with its own Colour, is a thing that you cannot (Pyrophilus,) but have often ſeen. The Solutions of Mercury in Aqua-fortis are not generally taken notice of, to give any notable Tincture to the Menſtruum; but ſometimes when the Liquor firſt falls upon the Quick Silver, I have obſerv'd a very remarkable, though not durable, Greenneſs, or Blewneſs to be produc'd, which is a Phænomenon not unfit for you to conſider, though I have not now the leiſure to diſcourſe upon it. Tin Corroded by Aqua-fortis till the Menstruum will work no farther on it, becomes exceeding White, but as we elſewhere note, does very eaſily of it ſelf acquire the conſiſtence, not of a Metalline Calx, but of a Coagulated matter, which we have obſerv'd with pleaſure to look ſo like, either to curdled Milk, or curdled Whites of Eggs, that a perſon unacquainted with ſuch Solutions may eaſily be miſtaken in it. But when I purpoſely prepar'd a Menſtruum that would diſſolve it as Aqua-fortis diſſolves Silver, and not barely Corrode it, and quickly let it fall again, I remember not that I took notice of any particular Colour in the Solution, as if the more Whitiſh Metalls did not much Tinge their Menſtruums, though the conſpicuouſly Colour'd Metalls as Gold, and Copper, do. For Lead diſſolv'd in Spirit of Vinegar or Aqua-fortis gives a Solution cleer enough, and if the Menſtruum be abſtracted appears either Diaphanous or White. Of the Colour of Iron we have elſewhere ſaid ſomething: And 'tis worth noting, that though if that Metall be diſſolv'd in oyl of Vitriol diluted with water, it affords a Salt or Magiſtery ſo like in colour, as well as ſome other Qualities, to other green Vitriol, that Chymiſts do not improperly call it Vitriolum Martis; yet I have purpoſely try'd, that, by changing the Menſtruum, and pouring upon the filings of Steel, inſtead of oyl of Vitriol, Aqua Fortis, (whereof as I remember, I us'd 4 parts to one of the Metall) I obtain'd not a Green, but a Saffron Colour Solution; or rather a thick Liquor of a deep but yellowiſh Red. Common Silver, ſuch as is to be met with in Coines, being diſſolv'd in Aqua fortis, yields a Solution tincted like that of Copper, which is not to be wondred at, becauſe in the coining of Silver, they are wont (as we elſewhere particularly inform you) to give it an Allay of Copper, and that which is ſold in ſhops for refined ſilver, is not (ſo far as we have tryed) ſo perfectly free from that ignobler Metall, but that a Solution of It in Aqua fortis, will give a Venereal Tincture to the Menſtruum. But we could not obſerve upon the ſolution of ſome Silver, which was perfectly refin'd, (ſuch as ſome that we have, from which 8 or 10 times its weight of Lead has been blown off) that the Menſtruum though held againſt the Light in a Cryſtal Vial did manifeſtly diſcloſe any Tincture, only it ſeem'd ſometimes not to be quite deſtitute of a little, but very faint Blewiſhneſs.
But here I muſt take notice, that of all the Metalls, there is not any which doth ſo eaſily and conſtantly diſcloſe its unobvious colour as Copper doth. For not only in acid Menſtruums as Aqua Fortis and Spirit of Vinegar, it gives a Blewiſh green ſolution, but if it be almoſt any way corroded, it appears of one of thoſe two colours, as may be obſerv'd in Verdigreeſe made ſeveral wayes, in that odd preparation of Venus, which we elſewhere teach you to make with Sublimate, and in the common Vitriols of Venus deliver'd by Chymiſts; and ſo conſtant is the diſpoſition of Copper, notwithſtanding the diſguiſe Artiſts put upon it, to diſcloſe the colour we have been mentioning, that we have by forcing it up with Sal Armoniack obtain'd a Sublimate of a Blewiſh Colour. Nay a famous Spagyriſt affirms, that the very Mercury of it is green, but till he teach us an intelligible way of making ſuch a Mercury, we muſt content ourſelves to inform you, that we have had a Cupreous Body, that was Præcipitated out of a diſtill'd Liquor, that ſeem'd to be the the Sulphur of Venus, and ſeem'd even when flaming, of a Greeniſh Colour. And indeed Copper is a Metall ſo eaſily wrought upon by Liquors of ſeveral kinds, that I ſhould tell you, I know not any Mineral, that will concurr to the production of ſuch a variety of Colours as Copper diſſol'd in ſeveral Menſtruums, as Spirit of Vinegar, Aqua fortis, Aqua Regis, Spirit of Nitre, of Urine, of Soot, Oyls of ſeveral kinds, and I know not how many other Liquors, if the variety of ſomewhat differing colours (that Copper will be made to aſſume, as it is wrought upon by ſeveral Liquors) were not comprehended within the Limits of Greeniſh Blew, or Blewiſh Green.
And yet I muſt advertiſe you (Pyrophilus) that being deſirous to try if I could not make with crude Copper a Green Solution without the Blewiſhneſs that is wont to accompany its Vulgar Solutions, I bethought my ſelf of uſing two Menſtruums, which I had not known imploy'd to work on this Metall, and which I had certain Reaſons to make Tryal of, as I ſucceſsfully did. The one of theſe Liquors (if I much miſremember not) was Spirit of Sugar diſtill'd in a Retort, which muſt be warily done, (if you will avoid breaking your glaſſes) and the other, Oyl or Spirit of Turpentine, which affords a fine Green Solution that is uſeful to me on ſeveral occaſions. And yet to ſhew that the adventitious colour may reſult, as well from the true and permanent Copper it ſelf, as the Salts wherewith 'tis corroded, I ſhall add, that if you take a piece of good Dantzick Copperis, or any other Vitriol wherein Venus is prædominant, and having moiſtened it in your Mouth, or with fair water, rubb it upon a whetted knife, or any other bright piece of Steel or Iron, it will (as we have formerly told you) preſent'y ſtain the Steel with a Reddiſh colour, like that of Copper, the reaſon of which, we muſt not now ſtay to inquire.
Annotation I.
I preſume you may have taken notice (Pyrophilus) that I have borrowed ſome of the Inſtances mention'd in this 47th Experiment, from the Laboratories of Chymiſts, and becauſe in ſome (though very few) other paſſages of this Eſſay, I have likewiſe made uſe of Experiments mention'd alſo by ſome Spagyrical Writers, I think it not amiſs to repreſent to you on this Occaſion once for all, ſome things beſides those which I intimated in the præamble of this preſent Experiment; For beſides, that 'tis very allowable for a Writer to repeat an Experiment which he invented not, in caſe he improve it; And beſides that many Experiments familiar to Chymiſts are unknown to the generality of Learned Men, who either never read Chymical proceſſes, or never underſtood their meaning, or never durſt believe them; beſides theſe things, I ſay, I ſhall repreſent, That, as to the few Experiments I have borrowed from the Chymiſts, if they be very Vulgar, 'twould perhaps be difficult to aſcribe each of them its own Author, and 'tis more than the generality of Chymiſts themſelves can do: and if they be not of very known and familiar practiſe among them, unleſs the Authors wherein I found them had given me cauſe to believe, themſelves had try'd them, I know not why I might not ſet them down, as a part of the Phænomena of Colours which I preſent you; Many things unanimouſly enough deliver'd as matters of fact by (I know not how many Chymical Writers) being not to be rely'd on, upon the ſingle Authority of ſuch Authors: For Inſtance, as ſome Spagyriſts deliver (perhaps amongſt ſeveral deceitful proceſſes) that Saccarum Saturni with Spirit of Turpentine will afford a Balſom, ſo Beguinus and many more tell us, that the ſame Concrete (Saccarum Saturni) will yield an incomparably fragrant Spirit, and a pretty Quantity of two ſeveral Oyles, and yet ſince many have complain'd, as well as I have done, that they could find no ſuch odoriferous, but rather an ill-ſented Liquor, and ſcarce any oyl in their Diſtillation of that ſweet Vitriol, a wary perſon would as little build any thing on what they ſay of the former Experiment, as upon what they averr of the later, and therefore I ſcrupled not to mention this Red Balſom of which I have not ſeen any, (but what I made) among my other experiments about redneſs.
Annot. II.
We have ſometimes had the Curioſity to try what Colours Minerals, as Tinglaſs, Antimony, Spelter, &c. would yield in ſeveral Menſtruums, nor have we forborn to try the Colours of ſtones, of which that famous one, (which Helmont calls Paracelſus's Ludus) though it be digg'd out of the Earth and ſeem a true ſtone, has afforded in Menſtruums capable to diſſolve ſo ſolid a ſtone, ſometimes a Yellowiſh, ſometimes a Red ſolution of both which I can ſhow you. But though I have from Minerals obtain'd with ſeveral Menſtruums very differing Colours, and ſome ſuch as perhaps you would be ſurpriz'd to ſee drawn from ſuch Bodies: yet I muſt now paſs by the particulars, being deſirous to put an End to this Treatiſe, before I put an end to your Patience and my own.
Annotation III.
And yet before I paſs to the next Experiment, I muſt put you in mind, that the Colours of Metals may in many caſes be further alter'd by imploying, either præcipitating Salts, or other convenient Subſtances to act upon their Solutions. Of this you may remember, that I have given you ſeveral Inſtances already, to which may be added ſuch as theſe, That if Quickſilver be diſſolv'd in Aqua fortis, and Præcipitated out of the Solution, either with water impregnated with Sea ſalt, or with the ſpirit of that Concrete, it falls to the Bottom in the form of a white powder, whereas if it be Præcipitated with an Alcaly, it will afford a Yellowiſh or tawny powder, and if there be no Præcipitation made, and the Menſtruum be drawn off with a convenient fire, the corroded Mercury will remain in the bottom, in the form of a ſubſtance that may be made to appear of differing Colours by differing degrees of Heat; As I remember that lately having purpoſely abſtracted Aqua fortis from ſome Quickſilver that we had diſſolv'd in it, ſo that there remain'd a white Calx, expoſing that to ſeveral degrees of Fire, and afterwards to a naked one, we obtain'd ſome new Colours, and at length the greateſt part of the Calx lying at the Bottome of the Vial, and being brought partly to a Deep Yellow, and partly to a Red Colour, the reſt appear'd elevated to the upper part and neck of the Vial, ſome in the form of a Reddiſh, and ſome of an Aſh-Colour Sublimate. But of the differing Colours which by differing wayes and working of Quick Silver with Fire, and Saline Bodies, may be produc'd in Precipitates, I may elſewhere have occaſion to take further notice. I alſo told you not long ſince, that if you corrode Quick-ſilver with Oyl of Vitriol inſtead of Aqua-fortis, and abſtract the Menſtruum, there will remain a White Calx which by the Affuſion of Fair Water preſently turns into a Lemmon Colour. And ev'n the Succedaneum to a Menſtruum may ſometimes ſerve the turn to change the Colours of a Metal. The lovely Red which Painters call Vermillion, is made of Mercury, which is of the Colour of Silver, and of Brimſtone which is of Kin to that of Gold, Sublim'd up together in a certain proportion, as is vulgarly known to Spagyriſts.
EXPERIMENT XLVIII.
The third chief ſort of the Adventitious Colours of Metals, is, that which is produc'd by aſſociating them (eſpecially when Calcin'd) with other fuſible Bodies, and Principally Venice, and other fine Glaſs devoid of Colour.
I have formerly given you an Example, whereby it may appear, that a Metal may impart to Glaſs a Colour much differing from its own, when I told you, how with Silver, I had given Glaſs a lovely Golden Colour. And I ſhall now add, that I have Learn'd from one of the Chief Artificers that ſells Painted Glaſs, that thoſe of his Trade Colour it Yellow with a preparation of the Calx of Silver. Though having lately had occaſion among other Tryals to mingle a few grains of Shell-ſilver (ſuch as is imploy'd with the Penſil and Pen) with a convenient proportion of powder'd Cryſtal Glaſs, having kept them two or three hours in fuſion, I was ſurpriz'd to find the Colliquated Maſs to appear upon breaking the Crucible of a lovely Saphirine Blew, which made me ſuſpect my Servant might have brought me a wrong Crucible, but he conſtantly affirm'd it to be the ſame wherein the Silver was put, and conſiderable Circumſtances countenanc'd his Aſſertion, ſo that till I have opportunity to make farther Tryal, I cannot but ſuſpect, either that Silver which is not (which is not very probable) brought to a perfect Fuſion and Colliquation with Glaſs, may impart to it other Colours than when Neal'd upon it, or elſe (which is leſs unlikely) that though Silver Beaters uſually chuſe the fineſt Coyn they can get, as that which is moſt extenſive under the Hammer, yet the Silver-leaves of which this Shel-ſilver was made, might retain ſo much Copper as to enable it to give the predominant tincture to the Glaſs.
For, I muſt proceed to tell you (Pyrophilus) as another inſtance of the Adventitious Colours of Metals, that which is ſomething ſtrange, Namely, That though Copper Calcin'd per ſe affords but a Dark and baſely Colour'd Calx, yet the Glaſsmen do with it, as themſelves inform me, Tinge their Glaſs green. And I remember, that when once we took ſome crude Copper, and by frequent Ignition quenching it in Water had reduc'd it to a Dark and Ill-colour'd Powder, and afterward kept it in Fuſion in about a 100. times its weight of fine Glaſs, we had, though not a Green, yet a Blew colour'd Maſs, which would perhaps have been Green, if we had hit right upon the Proportion of the Materials, and the Degree of Fire, and the Time wherein it ought to be kept in Fuſion, ſo plentifully does that Metal abound in a Venerial Tincture, as Artiſts call it, and in ſo many wayes does it diſcloſe that Richneſs. But though Copper do as we have ſaid give ſomewhat near the like Colour to Glaſs, which it does to Aqua-fortis, yet it ſeems worth inquiry, whether thoſe new Colours which Mineral Bodies diſcloſe in melted Glaſs, proceed from the Coalition of the Corpuſcles of the Mineral with the Particles of the Glaſs as ſuch, or from the Action (excited or actuated by fire) of the Alcalizate Salt (which is a main Ingredient of Glaſs,) upon the Mineral Body, or from the concurrence of both theſe Cauſes, or elſe from any other. But to return to that which we were ſaying, we may obſerve that Putty made by calcining together a proportion of Tin and Lead, as it is it ſelf a White Calx, ſo does it turn the Pitta di Cryſtallo (as the Glaſsmen call the matter of the Purer ſort of Glaſs, wherewith it is Colliquated into a White Maſs, which if it be opacous enough is employ'd, as we elſewhere declare, for White Amel. But of the Colours which the other Metals may be made to produce in Colourleſs Glaſs, and other Vitrifiable Bodies, that have native Colours of their own, I muſt leave you to inform your ſelf upon Tryal, or at leaſt muſt forbear to do it till another time, conſidering how many Annotations are to follow, upon what has in this and the two former Experiments been ſaid already.
Annotation I.
When the Materials of Glaſs being melted with Calcin'd Tin, have compos'd a Maſs Undiaphanous and White, this White Amel is as it were the Baſis of all thoſe fine Concretes that Goldſmiths and ſeveral Artificers imploy in the curious Art of Enamelling. For this White and Fuſible ſubſtance will receive into it ſelf, without ſpoyling them, the Colours of divers other Mineral ſubſtances, which like it will indure the fire.
Annotation II.
So that as by the preſent (XLVIII.) Experiment it appears, that divers Minerals will impart to fuſible Maſſes, Colours differing from their own; ſo by the making and compounding of Amels, it may appear, that divers Bodies will both retain their Colour in the fire, and impart the ſame to ſome others wherewith they were vitrifi'd, and in ſuch Tryals as that mention'd in the 17. Experiment, where I told you, that ev'n in Amels a Blew and Yellow will compound a Green. 'Tis pretty to behold, not only that ſome Colours are of ſo fix'd a Nature, as to be capable of mixture without receiving any detriment by the fire, that do's ſo eaſily deſtroy or ſpoyl thoſe of other Bodies; but Mineral Pigments may be mingled by fire little leſs regularly and ſucceſsfully, than in ordinary Dyeing Fatts, the vulgar Colours are wont to be mingled by the help of Water.
Annotation III.
'Tis not only Metalline, but other Mineral Bodies, that may be imploy'd, to give Tinctures unto Glaſs (and 'tis worth noting how ſmall a quantity of ſome Mineral ſubſtances, will Tinge a Comparatively vaſt proportion of Glaſs, and we have ſometimes attempted to Colour Glaſs, ev'n with Pretious Stones, and had cauſe to think the Experiment not caſt away. And 'tis known by them that have look'd into the Art of Glaſs, that the Artificers uſe to tinge their Glaſs Blew, with that Dark Mineral Zaffora, (ſome of my Tryals on which I elſewhere acquaint you) which ſome would have to be a Mineral Earth, others a Stone, and others neither the one, nor the other, but which is confeſſedly of a Dark, but not a Blew Colour, though it be not agreed of what particular Colour it is. 'Tis likewiſe though a familiar yet a remarkable practiſe among thoſe that Deal in the making of Glaſs, to imploy (as ſome of themſelves have inform'd me) what they call Manganeſs, and ſome Authors call Magneſia (of which I make particular mention in another Treatiſe) to exhibit in Glaſs not only other Colours than its own, (which is ſo like in Darkneſs or blackiſhneſs to the Load ſtone, that 'tis given by Mineraliſts, for one of the Reaſons of its Latine Name) but Colours differing from one another. For though they uſe it, (which is ſomewhat ſtrange) to Clarifye their Glaſs, and free it from that Blewiſh Greeniſh Colour, which elſe it would too often be ſubject to, yet they alſo imploy it in certain proportions, to tinge their Glaſs both with a Red colour, and with a Purpliſh or Murry, and putting in a greater Quantity, they alſo make with it that deep obſcure Glaſs which is wont to paſs for Black, which agrees very well with, and may ſerve to confirm what we noted near the beginning of the 44th Experiment, of the ſeeming Blackneſs of thoſe Bodies that are overcharg'd with the Corpuſcles of ſuch Colours, as Red, or Blew, or Green, &c. And as by ſeveral Metals and other Minerals we can give various Colours to Glaſs, ſo on the other ſide, by the differing Colours that Mineral Oars, or other Mineral Powders being melted with Glaſs diſcloſe in it, a good Conjecture may be oftentimes made of the Metall or known Mineral, that the Oar propos'd, either holds, or is moſt of kin to. And this eaſie way of examining Oars, may be in ſome caſes of good uſe, and is not ill deliver'd by Glauber, to whom I ſhall at preſent refer you, for a more particular account of it: unleſs your Curioſity command alſo what I have obſerv'd about theſe matters; only I muſt here advertiſe you, that great circumſpection is requiſite to keep this way from proving fallacious, upon the account of the variations of Colour that may be produc'd by the differing proportions that may be us'd betwixt the Oar and the Glaſs, by the Richneſs or Poorneſs of the Oar it ſelf, by the Degree of Fire, and (eſpecially) by the Length of Time, during which the matter is kept in fuſion; as you will eaſily gather from what you will quickly meet with in the following Annotation upon this preſent 48th Experiment.
Annotation IV.
There is another way and differing enough from thoſe already mention'd, by which Metalls may be brought to exhibit adventitious Colours: For by This, the Metall do's not ſo much impart a Colour to another Body, as receive a Colour from it, or rather both Bodies do by the new Texture reſulting from their miſtion produce a new Colour. I will not inſiſt to this purpoſe upon the Examples afforded us by yellow Orpiment, and common Sea Salt, from which, ſublim'd together, Chymiſts unanimouſly affirm their White or Cryſtalline Arſenick to be made: But 'tis not unworthy our noting, That though Yellow Orpiment be acknowledg'd to be the Copiouſeſt by far of the two Ingredients of Arſenick, yet this laſt nam'd Body being duely added to the higheſt Colour'd Metall Copper, when 'tis in fuſion, gives it a whiteneſs both within and without. Thus Lapis Calaminaris changes and improves the Colour of Copper by turning it into Braſs. And I have ſometimes by the help of Zinck duely mix'd after a certain manner, given Copper one of the Richeſt Golden Colours that ever I have ſeen the Beſt true Gold Ennobled with. But pray have a care that ſuch Hints fall not into any hands that may mis-imploy them.
Annotation V.
Upon the Knowledge of the differing wayes of making Minerals and Metalls produce their adventitious Colours in Bodies capable of Vitrification, depends the pretty Art of making what Chymiſts by a Barbarous Word are pleas'd to call Amanſes, that is counterfeit, or factitious Gemms, as Emeralds, Rubies, Saphires, Topazes, and the like. For in the making of theſe, though pure Sand or Calcin'd Cryſtal give the Body, yet 'tis for the moſt part ſome Metalline or Mineral Calx, mingled in a small proportion that gives the Colour. But though I have many years ſince taken delight, to divert my ſelf with this pleaſing Art, and have ſeen very pretty Productions of it, yet beſides that I fear I have now forgot moſt of the little Skill I had in it, this is no place to entertain you with what would rather take up an intire Diſcourſe, than be comprehended in an Annotation; wherefore the few things which I ſhall here take notice of to you, are only what belong to the preſent Argument, Namely,
Firſt, That I have often obſerv'd that Calcin'd Lead Colliquated with fine White Sand or Cryſtal, reduc'd by ignitions and ſubſequent extinctions in Water to a ſubtile Powder, will of it ſelf be brought by a due Decoction to give a cleer Maſs Colour'd like a German Amethyſt. For though this glaſs of Lead, is look'd upon by them that know no better way of making Amanſes, as the grand Work of them all, yet which is an inconvenience that much blemiſhes this way, the Calcin'd Lead it ſelf does not only afford matter to the Amanſes, but has alſo as well as other Metals a Colour of its own, which as I was ſaying, I have often found to be like that of German (as many call them) not Eaſtern Amethyſts.
Secondly, That nevertheleſs this Colour may be eaſily over-powr'd by thoſe of divers other Mineral Pigments (if I may ſo call them) ſo that with a glaſs of Lead, you may Emulate (for Inſtance) the freſh and lovely Greenneſs of an Emerald, though in divers caſes the Colour which the Lead it ſelf upon Vitrification tends to, may vitiate that of the Pigment, which you would introduce into the Maſs.
Thirdly, That ſo much ev'n theſe Colours depend upon Texture, that in the Glaſs of Lead it ſelf made of about three parts of Lytharge or Minium Colliquated with one of very finely Powder'd Cryſtal or Sand, we have taken pleaſure to make the mixture paſs through differing Colours, as we kept it more or leſs in the Fuſion. For it was not uſually till after a pretty long Decoction that the Maſs attain'd to the Amethyſtin Colour.
Fourthly and laſtly, That the degrees of Coction and other Circumſtances may ſo vary the Colour produc'd in the ſame maſs, that in a Crucible that was not great I have had fragments of the ſame Maſs, in ſome of which perhaps not ſo big as a Hazel-Nut, you may diſcern four diſtinct Colours.
Annotation VI.
You may remember (Pyrophilus) that when I mention'd the three ſorts of adventitious Colours of Metals, I mention'd them but as the chief, not the only. For there may be other wayes, which though they do not in ſo ſtrict a ſenſe belong to the adventitious Colours of Metals, may not inconveniently be reduc'd to them. And of theſe I ſhall name now a couple, without denying that there may be more.
The firſt may be drawn from the practiſe of thoſe that Dye Scarlet. For the famouſeſt Maſter in that Art, either in England or Holland, has confeſs'd to me, that neither others, nor he can ſtrike that lovely Colour which is now wont to be call'd the Bow-Dye, without their Materials be Boyl'd in Veſſels, either made of, or lin'd with a particular Metall. But of what I have known attempted in this kind, I muſt not as yet for fear of prejudicing or diſpleaſing others give you any particular Account.24
The other way (Pyrophilus) of making Metals afford unobvious Colours, is by imbuing divers Bodies with Solutions of them made in their proper Menſtruum's, As (for Inſtance) though Copper plentifully diſſolv'd in Aqua fortis, will imbue ſeveral Bodies with the Colour of the Solution; Yet Some other Metalls will not (as I elſewhere tell you) and have often try'd. Gold diſſolv'd in Aqua Regia, will, (which is not commonly known) Dye the Nails and Skin, and Hafts of Knives, and other things made of Ivory, not with a Golden, but a Purple Colour, which though it manifeſt it ſelf but ſlowly, is very durable, and ſcarce ever to be waſh'd out. And if I miſremember not, I have already told you in this Treatiſe, that the purer Cryſtals of fine Silver made with Aqua fortis, though they appear White, will preſently Dye the Skin and Nails, with a Black, or at leaſt a very Dark Colour, which Water will not waſh off, as it will ordinary Ink from the ſame parts. And divers other Bodies may the Same way be Dy'd, ſome of a Black, and others of a Blackiſh Colour.
And as Metalline, ſo likewiſe Mineral Solutions may produce Colours differing enough from thoſe of the Liquors themſelves. I ſhall not fetch an Example of this, from what we daily ſee happen in the powdring of Beef, which by the Brine imploy'd about it (eſpecially if the fleſh be over ſalted) do's oftentimes appear at our Tables of a Green, and ſometimes of a Reddiſh Colour, (deep enough) nor ſhall I inſiſt on the practiſe of ſome that deal in Salt Petre, who, (as I ſuſpected, and as themſelves acknowledg'd to me) do, with the mixture of a certain proportion of that; and common Salt, give a fine Redneſs, not only to Neats Tongues, but which is more pretty as well as difficult, to ſuch fleſh, as would otherwiſe be purely White; Theſe Examples, I ſay, I ſhall decline inſiſting on, as chuſing rather to tell you, that I have ſeveral times try'd, that a Solution of the Sulphur of Vitriol, or ev'n of common Sulphur, though the Liquor appear'd clear enough, would immediately tinge a piece of new Coin, or other clean Silver, ſometimes with a Golden, ſometimes with a deeper, and more Reddiſh colour, according to the ſtrength of the Solution, and the quantity of it, that chanc'd to adhere to the Metall; which may take off your wonder that the water of the hot Spring at Bath, abounding with diſſolv'd Subſtances of a very Sulphureous Nature, ſhould for a while, as it were gild, the new or clean pieces of Silver coyn, that are for a due time immers'd in it. And to theſe may be added thoſe formerly mention'd Examples of the adventitious Colours of Mineral Bodies; which brings into my mind, that, ev'n Vegetable Liquors, whether by degeneration, or by altering the Texture of the Body that imbibes them, may ſtain other Bodies with Colours differing enough, from their own, of which very good Herbariſts have afforded us a notable Example, by affirming that the Juice of Alcanna being green (in which ſtate I could never here procure it) do's yet Dye the Skin and Nails of a Laſting Red. But I ſee this Treatiſe is like to prove too bulky without the addition of further Inſtances of this Nature.
EXPERIMENT XLIX.
Meeting the other day, Pyrophilus, in an Italian book, that treats of other matters, with a way of preparing what the Author calls a Lacca of Vegetables, by which the Italians mean a kind of Extract fit for Painting, like that rich Lacca in Engliſh commonly call'd Lake, which is imploy'd by Painters as a glorious Red. And finding the Experiment not to be inconſiderable, and very defectively ſet down, it will not be amiſs to acquaint you with what ſome Tryals have inform'd us, in reference to this Experiment, which both by our Italian Author, and by divers of his Countrymen, is look'd upon as no trifling Secret.
Take then the root call'd in Latin Curcuma, and in Engliſh Turmerick, (which I made uſe of, becauſe it was then at hand, and is among Vegetables fit for that purpoſe one of the moſt eaſieſt to be had) and when it is beaten, put what Quantity of it you pleaſe into fair Water, adding to every pound of Water about a ſpoonfull or better of as ſtrong a Lixivium or Solution of Potaſhes as you can well make, clarifying it by Filtration before you put it to the Decocting water. Let theſe things boyl, or rather ſimper over a ſoft Fire in a clean glaz'd Earthen Veſſel, till you find by the Immerſion of a ſheet of White Paper (or by ſome other way of Tryal) that the Liquor is ſufficiently impregnated with the Golden Tincture of the Turmerick, then take the Decoction off the Fire, and Filter or Strain it that it may be clean, and leiſurely dropping into it a ſtrong Solution of Roch Allum, you ſhall find the Decoction as it were curdl'd, and the tincted part of it either to emerge, to ſubſide, or to ſwim up and down, like little Yellow flakes; and if you pour this mixture into a Tunnel lin'd with Cap Paper, the Liquor that Filtred formerly ſo Yellow, will now paſs clean thorow the Filtre, leaving its tincted, and as it were curdled parts in the Filtre, upon which fair Water muſt be ſo often pour'd, till you have Dulcifi'd the matter therein contain'd, the ſign of which Dulcification is (you know) when the Water that has paſs'd through it, comes from it as taſteleſs as it was pour'd on it. And if without Filtration you would gather together the flakes of this Vegetable Lake, you muſt pour a great Quantity of fair Water upon the Decoction after the affuſion of the Alluminous Solution, and you ſhall find the Liquor to grow clearer, and the Lake to ſettle together at the bottom, or emerge to the top of the Water, though ſometimes having not pour'd out a ſufficient Quantity of fair Water, we have obſerv'd the Lake partly to ſubſide, and partly to emerge, leaving all the middle of the Liquor clear. But to make this Lake fit for uſe, it muſt by repeated affuſions of freſh Water, be Dulcifi'd from the adhering Salts, as well as that ſeparated by Filtration, and be ſpread and ſuffer'd to dry leiſurely upon pieces of Cloth, with Brown Paper, or Chalk, or Bricks under them to imbibe the Moiſture25.
Annotation I.
Whereas it is preſum'd that the Magiſtery of Vegetables obtain'd this way conſiſts but of the more Soluble and Coloured parts of the Plants that afford it, I muſt take the liberty to Queſtion the ſuppoſition. And for my ſo doing, I ſhall give you this account.
According to the Notions (ſuch as they were) that I had concerning Salts; Allom, though to ſenſe a Homogeneous Body, ought not to be reckon'd among true Salts, but to be it ſelf look'd upon as a kind of Magiſtery, in regard that as Native Vitriol (for ſuch I have had) contains both a Saline ſubſtance and a Metall, whether Copper, or Iron, corroded by it, and aſſociated with it; ſo Allom which may be of ſo near a kin to Vitriol, that in ſome places of England (as we are aſſur'd by good Authority the ſame ſtone will ſometimes afford both) ſeems manifeſtly to contain a peculiar kind of Acid Spirit, generated in the Bowels of the Earth, and ſome kind of ſtony matter diſſolv'd by it. And though in making our ordinary Allom, the Workmen uſe the Aſhes of a Sea Weed (vulgarly call'd Kelp) and Urine: yet thoſe that ſhould know, inform us, that, here in England, there is beſides the factitious Allom, Allom made by Nature Without the help of thoſe Additaments. Now (Pyrophilus) when I conſider'd this compoſition of Allom, and that Alcalizate Salts are wont to Præcipitate what acid Salts have diſſolv'd, I could not but be prone to ſuſpect that the Curdled Matter, which is call'd the Magiſtery of Vegetables, may have in it no inconſiderable proportion of a ſtony ſubſtance Præcipitated out of the Allom by the Lixivium, wherein the Vegetable had been decocted, and to ſhew you, that there is no neceſſity, that all the curdl'd ſubſtance muſt belong to the Vegetable, I ſhall add, that I took a ſtrong Solution of Allom, and having Filtred it, by pouring in a convenient Quantity of a ſtrong Solution of Potaſhes, I preſently, as I expected, turn'd the mixture into a kind of white Curds, which being put to Filtre, the Paper retain'd a ſtony Calx, copious enough, very White, and which ſeem'd to be of a Mineral Nature, both by ſome other ſignes, and this, that little Bits of it being put upon a live Coal, which was Gently Blown whilſt they were on it, they did neither melt nor fly away, and you may keep a Quantity of this White ſubſtance for a good while, (nay for ought I can gueſs for a very long one) in a red hot Crucible without loſing or ſpoiling it; nor did hot Water wherein I purpoſely kept another parcel of ſuch Calx, ſeem to do any more than waſh away the looſer adhering Salts from the ſtony ſubſtance, which therefore ſeem'd unlikely to be ſeparable by ablutions (though reiterated) from the Præcipitated parts of the Vegetable, whoſe Lake is intended. And to ſhew you, that there is likewiſe in Allom a Body, with which the fix'd Salt of the Alcalizate Solution will concoagulate into a Saline Subſtance differing from either of them, I ſhall add, that I have taken pleaſure to recover out of the ſlowly exhal'd Liquor, that paſs'd through the filtre, and left the foremention'd Calx behind, a Body that at leaſt ſeem'd a Salt very pretty to look on, as being very White, and conſiſting of an innumerable company of exceeding ſlender, and ſhining Particles, which would in part eaſily melt at the flame of a Candle, and in part flye away with ſome little noiſe. But of this ſubſtance, and its odd Qualities more perhaps elſewhere; for now I ſhall only take notice to you, that I have likewiſe with Urinous Salts, ſuch as the Spirit of Sal Armoniack, as well as with the Spirit of Urine it ſelf, Nay, (if I much miſtake not) ev'n with Stale Urine undiſtil'd, eaſily Precipitated ſuch a White Calx as I was formerly ſpeaking of, out of a Limpid Solution of Allom, ſo that there is need of Circumſpection in judging of the Natures of Liquors by Precipitations wherein Allom intervenes, elſe we may ſometimes miſtakingly imagine that to be Precipitated out of a Liquor by Allom, which is rather Precipitated out of Allom by the Liquor: And this puts me in mind to tell you, that 'tis not unpleaſant to behold how quickly the Solution of Allom (or injected lumps of Allom) do's occaſion the ſevering of the colour'd parts of the Decoction from the Liquor that ſeem'd to have ſo perfectly imbib'd them.
Annot. II.
The above mention'd way of making Lakes we have tryed not only with Turmerick, but alſo with Madder, which yielded us a Red Lake; and with Rue, which afforded us an extract, of (almoſt if not altogether) the ſame Colour with that of the leaves.
But in regard that 'tis Principally the Alcalizate Salt of the Pot-aſhes, which enables the water to Extract ſo powerfully the Tincture of the Decocted Vegetables, I fear that our Author may be miſtaken by ſuppoſing that the Decoction will alwayes be of the very ſame Colour with the Vegetable it is made off. For Lixiviate Salts, to which Pot-aſhes eminently belong, though by peircing and opening the Bodies of Vegetables, they prepare and diſpoſe them to part readily with their Tincture, yet ſome Tinctures they do not only draw out, but likewiſe alter them, as may be eaſily made appear by many of the Experiments already ſet down in this Treatiſe, and though Allom being of an Acid Nature, its Solutions may in ſome Caſes deſtroy the Adventitious Colours produc'd by the Alcaly, and reſtore the former: yet beſides that Allom is not, as I have lately ſhown, a meer Acid Salt, but a mixt Body, and beſides, that its operations are languid in compariſon of the activity of Salts freed by Diſtillation, or by Incineration and Diſſolution, from the moſt of their Earthy parts, we have ſeen already Examples, that in divers Caſes an Acid Salt will not reſtore a Vegetable ſubſtance to the Colour of which an Alcalizate one had depriv'd it, but makes it aſſume a third very differing from both, as we formerly told you, that if Syrrup of Violets were by an Alcaly turn'd Green, (which Colour, as I have try'd, may be the ſame way produc'd in the Violet-leaves themſelves without any Relation to a Syrrup) an Acid Salt would not make it Blew again, but Red. And though I have by this way of making Lakes, made Magiſteries (for ſuch they ſeem to be) of Brazil, and as I remember of Cochinele it ſelf, and of other things, Red, Yellow or Green which Lakes were enobled with a Rich Colour, and others had no bad one; yet in ſome the colour of the Lake ſeem'd rather inferiour than otherwiſe to that of the Plant, and in others it ſeem'd both very differing, and much worſe; but Writing this in a time and place where I cannot provide my ſelf of Flowres and other Vegetables to proſecute ſuch Tryals in a competent variety of Subjects, I am content not to be poſitive in delivering a judgment of this way of Lakes, till Experience, or You, Pyrophilus, ſhall have afforded me a fuller and more particular Information.
Annotation III.
And on this occaſion (Pyrophilus) I muſt here (having forgot to do it ſooner) advertiſe you once for all, that having written ſeveral of the foregoing Experiments, not only in haſte but at ſeaſons of the year, and in places wherein I could not furniſh my ſelf with ſuch Inſtruments, and ſuch a variety of Materials, as the deſign of giving you an Introduction into the Hiſtory of Colours requir'd, it can ſcarce be otherwiſe but that divers of the Experiments, that I have ſet down, may afford you ſome matter of new Tryals, if you think fit to ſupply the deficiencies of ſome of them (eſpecially the freſhly mention'd about Lakes, and thoſe that concern Emphatical Colours) which deficiencies for want of being befriended with accommodations I could better diſcern than avoid.
Annotation IV.
The uſe of Allom is very great as well as familiar in the Dyers Trade, and I have not been ill pleas'd with the uſe I have been able to make of it in preparing other pigments than thoſe they imploy with Vegetable Juices. But the Lucriferous practiſes of Dyers and other Tradeſmen, I do, for Reaſons that you may know when you pleaſe, purpoſely forbear in this Eſſay, though not ſtrictly from pointing at, yet from making it a part of my preſent work explicitly and circumſtantially to deliver, eſpecially ſince I now find (though late and not without ſome Bluſhes at my prolixity) that what I intended but for a ſhort Eſſay, is already ſwell'd into almoſt a Volume.
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.