If Shoemakers put old Iron to this subject, they may therewith adorn their Leather with an excellent Black.
If Nitre be dissolv’d in Vinegar, and old Iron lie some time in it, it will make an Ink with which Hides may be blacked with an excellent Black. But there is no need of Nitre for this use, for if Iron be put to Aqua Calcis, it effecteth the same thing; only mention is made of this in Miraculum Mundi, that it might be manifest, that this Universal Subject may be of use, to all and singular Artificers.
Point XVI.
Weavers may render their Linen Threds so fine and soft, that they will emulate silk.
All Men know that the boiling of Thread in a strong Lixivium renders it soft and delicate, but seeing that fixed Nitre is better than a strong Lixivium, it will also perform this work better than any common Lixivium.
Point XVII.
Dyers by this may give so firm and unchangeable a ground, to their Cloth, that the superinduced Colours shall not be corrupted, or spoiled by any Wine, Vinegar, Urine, Pickles, Air, or Sun.
If the Spirit of Nitre be put into the first boiling with the Alum and Tartar, for the aluminating the Cloths, it will give a permanent ground, as is already proved in the fourth point.
Point XVIII.
Potters may thence prepare a Glassy Colour, not unlike to the Indian Porcellane, of which Vessels may be made having the aspect of Gold, Silver, or Copper, a singular Ornament for Noblemens Tables, hitherto unknown to the World.