Experiment XV
And now, Pyrophilus, it will not be improper for us to take ſome notice of an Opinion touching the cauſe of Blackneſs, which I judged it not ſo ſeaſonable to Queſtion, till I I had ſet down ſome of the Experiments, that might juſtifie my diſſent from it. You know that of late divers Learned Men, having adopted the three Hypoſtatical Principles, beſides other Notions of the Chymiſts, are very inclinable to reduce all Qualities of Bodies to one or other of thoſe three Principles, and Particularly aſſign for the cauſe of Blackneſs the Sootie ſteam of adust or torrifi’d Sulphur. But I hope that what we have deliver’d above to countenance the Opinion we have propos’d about the Cauſe of Blackneſs, will ſo eaſily ſupply you with ſeveral Particulars that may be made uſe of againſt this Opinion, that I ſhall now repreſent to You but two things concerning it.
And Firſt it ſeems that the favourers of the Chymicall Theories might have pitcht upon ſome more proper term, to expreſs the Efficient of Blackneſs than Sulphur adust; for we know that common Sulphur, not only when Melted, but even when Sublim’d, does not grow Black by ſuffering the Action of the fire, but continues and aſcends Yellow, and rather more than leſs White, than it was before its being expos’d to the fire. And if it be ſet on fire, as when we make that acid Liquor, that Chymiſts call Oleum Sulphuris per campanam, it affords very little Soot, and indeed the flame yeelds ſo little, that it will ſcarce in any degree Black a ſheet of White Paper, held a pretty while over the flame and ſmoak of it, which is obſerved rather to Whiten than Infect linnen, and which does plainly make Red Roſes grow very Pale, but not at all Black, as far as the Smoak is permitted to reach the leaves. And I can ſhew you of a ſort of fixt Sulphur made by an Induſtrious Laborant of your acquaintance, who aſſur’d me that he was wont to keep it for divers weeks together night and day in a naked and Violent fire, almoſt like that of the Glaſs-houſe, and when, to ſatisfie my Curioſity, I made him take out a lump of it, though it were glowing hot (and yet not melted,) it did not, when I had ſuffered it to cool, appear Black, the true Colour of it being a true Red. I know it may be ſaid, that Chymiſts in the Opinion above recited mean the Principle of Sulphur, and not common Sulphur which receives its name, not from its being all perfectly of a Sulphureous Nature, but for that plenty and Predominancy of the Sulphureous Principle in it. But allowing this, ’tis eaſie to reply, that ſtill according to this very Reaſon, torrifi’d Sulphur ſhould afford more Blackneſs, than moſt other concretes, wherein that Principle is confeſs’d to be far leſs copious. Alſo when I have expos’d Camphire to the fire in Cloſe Veſſels, as Inflamable, and conſequenly (according to the Chymiſts) as Sulphureous a Body as it is, I could not by ſuch a degree of Heat, as brought it to Fuſion, and made it Boyl in the glaſs, impreſs any thing of Blackneſs, or of any other Colour, than its own pure White, upon this Vegetable concrete. But what ſhall we ſay to Spirit of Wine, which being made by a Chymical Analyſis of the Liquor that affords it, and being totally Inflamable, ſeems to have a full right to the title they give it of Sulphur Vegetabile, & yet this fluid Sulphur not only contracts not any degree of Blackneſs by being often ſo heated, as to be made to Boyl, but when it burns away with an Actual flame, I have not found that it would diſcolour a piece of White Paper held over it, with any diſcernable ſoot. Tin alſo, that wants not, according to the Chymiſts, a Sulphur Joviale, when throughly burned by the fire into a Calx, is not Black, but eminently White. And I lately noted to you out of Bellonius, that the Charcoals of Oxy-cedar are not of the former of theſe two Colours, but of the latter. And the Smoak of our Tinby coals here in England, has been uſually obſerv’d, rather to Blanch linnen then to Black it. To all which, other Particulars of the like nature might be added, but I rather chooſe to put you in mind of the third Experiment, about making Black Liquors, or Inks, of Bodies that were non of them Black before. For how can it be ſaid, that when thoſe Liquors are put together actually Cold, and continue ſo after their mixture, there intervenes any new Adustion of Sulphur to produce the emergent Blackneſs? (and the ſame queſtion will be appliable to the Blackneſs produc’d upon the blade of a Knife, that has cut Lemmons and ſome kind of Sowr apples, if the juyce (though both Actually and Potentially Cold) be not quickly wip’d of) And when by the inſtilling either of a few drops of Oyl of Vitriol as in the ſecond Experiment, or of a little of the Liquor mention’d in the Paſſage pointed at in the fourth Experiment, (where I teach at once to Deſtroy one black Ink, and make another) the Blackneſs produc’d by thoſe Experiments is preſently deſtroy’d; if the Colour proceeded only from the Plenty of Sulphurous parts, torrify’d in the Black Bodies, I demand, what becomes of them, when the Colour ſo ſuddenly diſſappears? For it cannot Reaſonably be ſaid, that all thoſe that ſuffic’d to make ſo great a quantity of Black Matter, ſhould reſort to ſo very ſmall a proportion of the Clarifying Liquor, (if I may ſo call it) as to be deluted by it, with out at all Denigrating it. And if it be ſaid that the Inſtill’d Liquor diſpers’d thoſe Black Corpuſcles, I demand, how that Diſperſion comes to deſtroy their Blackneſs, but by making ſuch a Local Motion of their parts, as deſtroys their former Texture? which may be a Matter of ſuch moment in caſes like ours, that I remember that I have in few houres, without addition, from Soot it ſelf, attain’d pretty ſtore of Cryſtalline Salt, and good ſtore of Tranſparent Liquor, and (which I have on another occaſion noted as remarkable) this ſo Black Subſtance had its Colour ſo alter’d, by the change of Texture it receiv’d from the fire, wherewith it was diſtill’d, that it did for a great while afford ſuch plenty of very white Exhalations, that the Receiver, though large, ſeem’d to be almoſt fill’d with Milk.
Secondly, But were it granted, as it is in ſome caſes not Improbable, that divers Bodies may receive a Blackneſs from a Sootie Exhalation, occaſion’d by the Aduſtion of their Sulphur, which (for the Reaſons lately mention’d I ſhould rather call their Oyly parts;) yet ſtill this account is applicable but to ſome Particular Bodies, and will afford us no General Theory of Blackneſs. For if, for example, White Harts-horn, being, in Veſſels well luted to each other, expos’d to the fire, be ſaid to turn Black by the Infection of its own Smoak, I think I may juſtly demand, what it is that makes the Smoak or Soot it ſelf Black, ſince no Such Colour, but its contrary, appear’d before in the Harts-horn? And with the ſame Reaſon, when we are told, that torrify’d Sulphur makes bodies Black, I deſire to be told alſo, why Torrefaction makes Sulphur it ſelf Black? nor will there be any Satisfactory Reaſon aſſign’d of theſe Quæries, without taking in thoſe Fertile as well as intelligible Mechanical Principles of the Poſition and Texture of the Minute parts of the body in reference to the Light and the Eye; and theſe applicable Principles may Serve the turn in many caſes, where the Aduſtion of Sulphur cannot be pretended; as in the appearing Blackneſs of an Open window, lookt upon at a ſomewhat remote diſtance from the houſe, as alſo in the Blackneſs Men think they ſee in the Holes that happen to be in White linnen, or Paper of the like Colour; and in the Increaſing Blackneſs immediatly Produc’d barely by ſo rubbing Velvet, whoſe Piles were Inclin’d before, as to reduce them to a more Erected poſture, in which and in many other caſes formerly alleg’d, there appears nothing requiſite to the Production of the Blackneſs, but the hindering of the incident Beams of Light from rebounding plentifully enough to the Eye. To be ſhort, thoſe I reaſon with, do concerning Blackneſs, what the Chymiſts are wont alſo to do concerning other Qualities, namely to content themſelves to tell us, in what Ingredient of a Mixt Body, the Quality enquir’d after, does reſide, inſtead of explicating the Nature of it, which (to borrow a compariſon from their own Laboratories) is much as if in an enquiry after the cauſe of Salivation, they ſhould think it enough to tell us, that the ſeveral Kinds of Præcipitates of Gold and Mercury) as likewiſe of Quick-ſilver and Silver (for I know that make and uſe of ſuch Precipitates alſo) do Salivate upon the account of the Mercury, which though Diſguis’d abounds in them, whereas the Difficulty is as much to know upon what account Mercury it ſelf, rather than other Bodies, has that power of working by Salivation. Which I ſay not, as though it were not ſomething (and too often the moſt we can arrive at) to diſcover in which of the Ingredients of a Compounded Body, the Quality, whoſe Nature is ſought, reſides, but becauſe, though this Diſcovery it ſelf may paſs for ſomething, and is oftentimes more than what is taught us about the ſame ſubjects in the Schools, yet we ought not to think it enough, when more Clear and Particular accounts are to be had.