CHAP. CCVII. To make Red Colour for Glass Paint.
THIS requires as much caution as the Blue: You must take Scales of Iron, and Litharge of Silver, of each a Dram, Feretto of Spain half a Dram, Rocaille three Drams and half; grind all these for half an Hour on a shallow Copper-Plate, in the mean time pound three Drams of Blood-Stone in an Iron-Mor∣tar, and add it to the rest; then pound a Dram of Gum-Arabick in that Mortar to an impalpable Pow∣der, to take off the remains of your Blood-stone, and so add it to the rest, grinding them still continually, lest the Blood-stone be spoiled.
The best manner of grinding these is to pour Wa∣ter by little and little on the Ingredients as you grind them, neither wetting them too much, nor too lit∣tle, but just as much as will keep a good Temper as for Painting: Afterwards put all into a foot Glass, and so drop on it through a small hollow Cane of Wood, or with your Finger, as much Water as will bring it to the consistence of an Eggs-Yolk buttered, or a little more, then cover the Glass to preserve it from Dust, and so let it stand three Days to settle. After this, decant the clearest and purest of the Co∣lours that rise at top, into another Glass, without