The Glasing of Earthen Vessels, that they may appear like a natural Metal, is an egregious art, but it doth not always succeed, for the Colours are easily burnt and destroyed by too much heat, so that no Metallick Vitrification can be discerned. Vessels therefore, ought to be glased not in a common Potters Furnace, but in a peculiar Furnace, that the fire may be oftner observed. If the Vitrification be to represent Gold, or Silver, or Copper, then Gold, and Silver, and Copper is also to be taken in this manner: Take one part of Gold and Silver, or Copper, Regulus of Antimony two or four parts, melt the Regulus and the Metal, pulverise them in an Iron Mortar, and mix them with an equal portion of Nitre, suffer the mixture to be fixed in a Crucible, with which mixture the earthen vessel is to be rubbed over or gilded, afterwards to be committed to a Furnace fit for this purpose; if you proceed right, you will obtain a very beautiful Vitrification, as if the Vessel was gilt with Gold, Silver, or Copper, which will not vanish or decay, and will far exceed in beauty and splendour the Vessels which are gilt with those Metals, for those in process of time lose their splendour, but these do not as long as the least bit remains.
Point XIX, and XX.
Souldiers, Merchants, Travellers, Carriers, Fishermen, and others, who are much in the open Air, may of this prepare a Varnish in which they may dip linen Cloth, which will not permit either Air or Water to pass through it, with which they may defend their Boots or Cloths, so that they may travel dry in the rain. They who make Tapestry, may restore their faint and faded Colours, so that they shall be strong and beautiful.
Here mention is made of a certain mixture in which if Linen Cloth be dipped and dryed will not permit water to pass through, and it is done in this manner. There is nothing wanting in Linseed Oyl, but that the humidity be taken from it, which always hindereth its dying; now to effect that, there is no better way, than to boil the Linseed Oyl gently and gradually with the Flowers of Lapis Calaminaris or Saturn, (which are sublimed by Nitre) so long till the Oyl be tenacious, and groweth hard enough for this use. NB. That a Linen Cloth immersed in this mixture, and shining Talk being finely laid upon it, may be coloured of any colour, which will very strongly adhere to it, and may serve for the making of Tapestry. Therefore in this manner the nineteenth and twentieth Points are confirmed.
Point XXI, and XXII.
Mistresses of Families, may of it prepare fine Soap or Wash:balls, far exceeding the Venetian. Houshold Maids, may with it scour their Metalline Vessels, so as to render them neat and beautiful.
That fixed Nitre will wash and purifie Linen cloth beyond all Soap, no Man will deny, who comprehendeth the matter, concerning which thing, the Ancients have written much, and not in vain, calling Nitre the Soap of the wise, but not for the washing of Womens Linen, but for the intrinsecal purifying of the imperfect Metals: Their External Purgation may also be performed by help thereof, so that the twenty second Point is also verified.
Point XXIII.
Women may change the Yellow, Pale, or Brown Colour of their Face, and hands, into a beautiful whiteness.
That an Egregious Cosmetick may be made of Nitre, calcined with white Talk (by which ill coloured skins may be whitened) is not to be doubted. For if Nitre fixed by the Regulus of Antimony alone, performeth that, why should it not yet do it better, if it be conjoined with some white Mineral Talk in the Calcination?