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 Caeruleous 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 Caeruleous, 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 Phaenomena 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