The works of the Honourable Robert Boyle, Esq., epitomiz'd by Richard Boulton ... ; illustrated with copper plates.

TITLE XI. Of Salts in the Air.

* 1.1THO' the Peripateticks teach, that the Air is an Element, and consequently a pure simple Body, whose Qualities are moist and dry; yet from what we have already deliver'd, it ap∣pears, that it is an Aggregate of various kind of Effluvia jumbled and mix'd together; I mean, the Air distinct from that Purer Substance Ae∣ther, which I suppose diffus'd through the In∣terstellar Part of the Universe.

Amongst the Effluvia which rove up and down the Air; I account Saline ones the Chief, which is not unlikely, since the Terraqueous Globe, which continually emits Effluvia, abounds with great Quantities of Marine, Aluminous and Vitriolate Salts, which impregnate the Air; besides several Exhalations rais'd by the Sun-Beams, from the Surface of the Earth and Water; not to mention several other Saline Vapours which are dispersed in the Atmosphere, and arise from Vulcanos, as well as common Fires.

And as it is not improbable, but that the Air plentifully abounds with Saline Effluvia; so very likely, besides Nitrous, there are other kinds raised up and roving about in it; as Common Salt, and Vitriolate Salts; and that which seems to prove, that the Air in some places abounds with vitriolate Salts, is, that it hath been observ'd, that Hinges have been corroded and rotted, and other things prejudic'd upon a Vitriolate Soil, whereas in Houses, which stood on a Chalky Soil, no such Effects were observ'd: Be∣sides, on the Vitriolate Ground, we took No∣tice of Saline and White Efflorescences upon the Surface of the Soil, when beaten upon by the Sun-beams.

Besides which kinds of Salt, I am induc'd to believe, that the Air abounds with Volatile ones; For besides, that an Acquaintaince of Mine obtained a Spirit and Salt of Similar Qualities with Spirit of Harts-horn from Earth dug up some Yards deep; we may observe in favour of what I propose, that the very Soot which rises from fires near great Towns, a great part of which is dispersed in the Air, abounds with a Saline Spi∣rit, which may be obtain'd from it by Distillati∣on; as likewise, a great quantity of Volatile Matter may be raised in the form of Va∣pours from Animal substances putrified and cor∣rupted.

But besides these more simple Salts, there may be several others compounded in the Air, which may result from several Coalitions of simple Salts; and several Compound Salts may, not unlikely, arise from Subterraneal Parts: In favour of which I shall add, that in

America the Effluvia of a Vulcano, not only of∣fended, the Faces of some that approach'd too near, but caused a manifest alteration in the Colour of their Hair. And it hath been ob∣serv'd that several Sulphureous Exhalations have been gathered about the Crannies of Mount Ve∣suvius, which issuing out of small Crannies stick to the Edges like Flower of Brimstone: To which I shall add, that I had a Stone brought me from another Vulcano, whose Pores were full of a White Salt compounded of a fixed one, and an∣other Volatile much like Sal-Armon.

The Salts we have hitherto taken Notice of, are such as may be referred to a determinate Species: But I am apt to believe, that there are others which are such as are not known, nor have they any Names given them; this appears from what we have elsewhere taught of Sub∣terraneal Fumes; and may be further illustrated, by intimating, that I have observ'd Old Glass-windows sometimes corroded, as if Worm-eaten; which probably proceeded from some corrosive Particles carried thither by the Wind.

As for the Nature of these several Salts, that at different times, and in various Places, impreg∣nate the Air, amongst the different Methods that might be taken to investigate them, I shall mention the following.

• ...* 1.2 First, We may expose such Bodies to the Air, as we think will most likely be work'd upon, by the Salt we judge Predominant in that place; as Lime, where we think Nitre abounds; as also we may hang up Silks of such Colours as Nitre is most apt to fade, or discolour. In

• places where we think Vitriol abounds we may expose Preparations of Sulphur, which it usual∣ly turns Black: In other Places we may spread White Linnen Cloths, and observe what Salts they imbibe along with the Rising Vapours and Falling Dew.
• A Second way to discover the Nature of the Salts in the Air may be, by exposing some Body, which several Salts have different Effects on.

EXPERIMENT I.

CLean Copper Plates being placed over Glasses, under which, Spirit of Salt and Spirit of Nitre diluted with Water, were set. I Oserved, that they were discoloured alike by the ascending Fumes; it being common for these Spirits to draw a green Tincture from Copper as Spirit of Soot and Urine do a Blew one. I have observed a piece of Copper brought from a Mine overcast in several Parts with a Verdi∣grease, which effect I judged to depend on the Efficacy of some Effluvia in the Air. And possi∣bly with other Bodies, discovering different dis∣colourations, we be enabled to learn what kind of Steams those Effects are produced by. And it hath been observ'd, not only at Amsterdam, but elsewhere, that Plate, in a little time, in those Airs, would acquire a Rusty Colour, or one partaking of Yellow and Black.

A Third way, which may be taken to dis∣cover the different Nature of Effluvia, may be

by exposing Preparations of Mineral Bodies, whose Colours are apt to be changed by the Air.

EXPERIMENT II.

IF a Solution of Silver in Aq. Fortis be preci∣pitated with Spirit of Sea Salt, the Powder will be at the First White; but after a while be∣ing exposed to the Air, the Surface of the Liquor will acquire a dark Colour, which may perhaps vary as the Air is differently impregnated.

EXPERIMENT III.

AN equal Weight of Filings of Copper and Powdered Sal Armoniack, being mixed and put into a Covered Crucible, and kept over a moderate Fire till the Sal Armon. had done Smoaking, as much of the remaing Mass as could be parted was taken out, and looked of a Dark Colour; but being grossly beaten and exposed to the Air, looked like Verdigrease, a substance whose Colour commonly varies, according to the Nature of the Salts concerned in the producti∣on of the Pigment. But a Parcel of the same Mass being grosly beaten, and Hermetically Sealed up from the Air, and left in a South Win∣dow, was not discoloured when that exposed to the Air, had acquired a Virdigrease Colour.

EXPEREMENT. IV.

SPirit of Soot of Wood dissolved Copper in∣to a lovely Azure; but the substance grow∣ing dry in the Air, changed it's Ceruleous for a Cyanious Colour, such as may be seen in good Turquoises. Which Change depended not on the Saline-Sulphureous Salt. Which I rather believe, because I had the same success when I made use of an Urinous Spirit drawn from an Animal substance.

Most of the Inland Parts of our Country a∣bound not with Corrosive Vapours, the Bars of Iron being not so subject to be corroded and Rust; So that I believe this Salt may proceed from Sea Vapours, or a dissolution of some Cor∣roding Salt, upon the burning of a Sea, or Mineral Coals.

Mox ollam ex igni removent;* 1.3 postea ex refrige∣rata eximunt halinitrum purissimum: quod candidi marmoris speciem gerit; aet{que} tunc etiam id quod ter∣renum est, in fundo residet. At terra, ex qua dilu∣tum fuit factum, & Rami quernei vel consimilis Arbo∣ris alternis sub dio ponantur, & aqua quâ combibit halinitrum conspergantur: quo modo quin{que} vel sex annis rursus apta fit ad conficiendum dilutum. Ha∣linitrum quodammodo purum, quod dum terra tot annos quievit interea, ortum fuit, & quod lapidei parietes in Cellis Ʋrinariis & locis opacis exudant, cum primo diluto permistum decoquatur.

Si verò locus aliquis talium venarum, copiam sup∣peditaverit, ipsae statim non conjiciantur in cast ella;

sed primò convehantur in areas, at{que} cumulentur: quanto enim diutius aeri & pluviis expositae fuerint tanto meliores fiunt. Nam in ejus∣modi cumulis, aliquot post Mensibus, quam Venae in are as fuerint conjectae, nascuntur fibrae longe venis bonitate praestantes: deinde vehantur in sex, plurave Castella longa & lat a ad novem pedes, ad quin{que} alta.

Si verò dum dilutum recoquitur, seperata non fue∣rint, mox ex minoribus Vasis infundatur in Majora, ea{que} concludantur; in quibus item atramentum suto∣rium seperatum ab alumine concrescit utrum{que} inci∣sum & in Hypocausto siccatum divendatur dilutum, quod in vasis & cupis non concrevit in cortinam, re∣fusum recoquatur: sed verra, quae in fundo cujus{que} cortinae resedit, ablata in castella unà cum verra; de∣nuo aqua & urina dilutaur. At terra quae in Castel∣lis diluta, postquam effluxit, superfuit egesta & coa∣cervata quotidie, rursus magis ac magis fit aluminosa, non aliter at{que} terra, ex qua halinitrum fuit con∣fectum, suo succo plenior fit: quare denuo in Castel∣la conjicitur, & aquae effusae ea percolantur.

And I have not only been informed, that the Dews in the most Southern parts are more than ordinary Corrosive; but that in Basil they are so Esurient, that the Portugals are forc'd to keep their great Guns cased up; in which Country the same Person told me the very Mony was cor∣roded by the sharpness of the Air; and he like∣wise observed, that the Dew left a White Salt upon the Grass, which looked like a Hoar Frost.

And I am likewise inform'd by a Native of the Place, that in a Town call'd Fahlure in Sweedland,

which stands upon the bottom of a Hill, which hath a Copper Mine in it, The Exhalations are so powerful as to Corrode Iron and Brass, and even Money it self, tho' lock'd up in Chests of Wood an Inch thick.

Notes

• * 1.1

  Of the Salts in the Air.
• * 1.2

  Several ways to discover the Nature of the Salts in the Air.
• * 1.3

  Agricola de re Metal. Lib. 12.