EXPERIMENT IX.
We took a Leaf of Such Foliated Gold as Apothecaries are wont to Gild their Pills with; and with the Edge of a Knife, (lightly moyſten'd by drawing it over the Surface of the Tongue, and afterwards) laid upon the edge of the Gold Leaf; we ſo faſten'd it to the Knife, that being held againſt the light, it conctinu'd extended like a little Flagg. This Leaf being held very near the Eye, and obverted to the Light, appear'd ſo full of Pores, that it ſeem'd to have ſuch a kind of Tranſparency as that of a Sive, or a piece of Cyprus, or a Love-Hood; but the Light that paſs'd by theſe Pores was in its Paſſages So Temper'd with Shadow, and Modify'd, that the Eye diſcern'd
no more a Golden Colour, but a Greeniſh Blew. And for other's ſatisfaction, we did in the Night look upon a Candle through ſuch a Leaf of Gold; and by trying the Effect of Several Proportions of Diſtance betwixt the Leaf, the Eye and the Light, we quickly hit upon ſuch a Poſition for the Leaf of Gold, as that the flame, look'd on through it, appear'd of a Greeniſh Blew, as we have ſeen in the Day time. The like Experiment try'd with a Leaf of Silver ſucceeded not well.
EXPERIMENT X.
We have ſometimes found in the Shops of our Druggiſts, a certain Wood, which is there called Lignum Nephriticum, becauſe the Inhabitants of the Country where it grows, are wont to uſe the Infuſion of it made in fair Water againſt the Stone of the Kidneys, and indeed an Eminent Phyſician of our Acquaintance, who has very Particularly enquir'd into that Diſeaſe, aſſures me, that he has found ſuch an Infuſion one of the moſt effectual Remedyes, which he has ever tried againſt that formidable Diſeaſe. The ancienteſt Account I have met with of this Simple, is given us by the Experienc'd Monardes in theſe Words.
Nobis, ſays he,[a]16] Nova Hiſpania mittit quoddam ligni genus craſſum & enode, cujus uſus jam diu receptus fuit in his Regionibus ad Renum vitia & urinæ difficultates ac arenulas pellendas. Fit autem hac ratione, Lignum aſſulatim & minutim conciſum in limpidiſſima aqua fontana maceratur, inque ea relinquitur, donec aqua à bibentibus abſumpta ſit, dimidia hora post injectum lignum aqua cæruleum colorem contrabit, qui ſenſim intenditur pro temporis diuturnitate, tametſi lignum candidum fit. This Wood, Pyrophilus, may afford us an Experiment, which beſides the ſingularity of it, may give no ſmall aſſiſtance to an attentive Conſiderer towards the detection of the Nature of Colours. The Experiment as we made it is this. Take Lignum Nephriticum, and with a Knife cut it into thin Slices, put about a handfull of theſe Slices into two three or four pound of the pureſt Spring-water, let them infuſe there a night, but if you be in haſt, a much ſhorter time may ſuffice; decant this Impregnated Water into a clear Glaſs Vial, and if you hold it directly between the Light and your Eye, you ſhall ſee it wholly Tincted (excepting the very top of the Liquor, wherein you will ſome times diſcern a Sky-colour'd Circle) with
an almoſt Golden Colour, unleſs your Infuſion have been made too Strong of the Wood, for in that caſe it will againſt the Light appear ſomewhat Dark and Reddiſh, and requires to be diluted by the addition of a convenient quantity of fair Water. But if you hold this Vial from the Light, ſo that your Eye be plac'd betwixt the Window and the Vial, the Liquor will appear of a deep and lovely Cæruleous Colour, of which alſo the drops, if any be lying on the outſide of the Glaſs, will ſeem to be very perfectly; And thus far we have try'd the Experiment, and found it to Succeed even by the Light of Candles of the larger ſize. If you ſo hold the Vial over againſt your Eyes, that it may have a Window on one ſide of it, and a Dark part of the Room both before it and on the other ſide, you ſhall ſee the Liquor partly of a Blewiſh and partly of a Golden Colour. If turning your back to the Window, you powr out ſome of the Liquor towards the Light and towards your Eyes, it will ſeem at the comming out of the Glaſs to be perfectly Cæruleous, but when it is fallen down a little way, the drops may ſeem Particolour'd, according as the Beams of Light do more or leſs fully Penetrate and Illuſtrate them. If you take a Baſon about
half full of Water, and having plac'd it ſo in the Sun-beams Shining into a Room, that one part of the Water may be freely illuſtrated by the Beams of Light, and the other part of it Darkned by the ſhadow of the Brim of the Baſon, if then I ſay you drop of our Tincture, made ſomewhat ſtrong, both into the Shaded and Illuminated parts of the Water, you may by looking upon it from ſeveral places, and by a little Agitation of the water, obſerve divers pleaſing Phænomena which were tedious to particularize. If you powr a little of this Tincture upon a ſheet of White Paper, ſo as the Liquor may remain of ſome depth upon it, you may perceive the Neighbouring drops to be partly of one Colour, and partly of the other, according to the poſition of your Eye in reference to the Light when it looks upon them, but if you powr off all the Liquor, the Paper will ſeem Dy'd of an almoſt Yellow Colour. And if a ſheet of Paper with ſome of this Liquor in it be plac'd in a window where the Sunbeams may ſhine freely on it, then if you turn your back to the Sun and take a Pen or ſome ſuch ſlender Body, and hold it over-thwart betwixt the Sun and the Liquor, you may perceive that the Shadow projected by the Pen upon the Liquor, will not all of it be a vulgar
and Dark, but in part a curiouſly Colour'd ſhadow, that edge of it, which is next the Body that makes it, being almoſt of a lively Golden Colour, and the remoter verge of a Cæruleous one.