White is not a Colour in it self, but only a Faculty or Disposition in Bodies to receive Colour: When it is exposed in the open Air, its Shadows do all appear Blueish, because the Surface of every Opake Body partakes of the Colour of the Object that illumines it. If it be screen'd from the Light of the Sun by the interposition of any Opake Body, it will remain Blank, without the appearance of any Colour whatever. When it is exposed to the Light of the Sun, and the Air, it participates of the Colour both of the one and the other; that part of it turn'd from the Sun, appearing obscure, being tinged with the Azure of the Air alone: Lastly, White if secured both from the Greenness of the Champagne, and the Whiteness of the Horizon around, wou'd, without doubt, appear simply and without alteration, of the Colour of the Air.