BEsides the Polypody, the Oak produces Acorns which are its proper Fruit, and every Body pretends to make and sell the Oil; but as I never saw any to this Day, I shall say nothing of it, but that all the Oil of Acorns that the People of Provence send us, is nothing but the Ben or Nut Oil, in which the Acorn has been infus'd. The great Rarity of this Oil, is the Reason that the World attributes such great Virtues to it, just like that of the true Oil of Talck: There may be a true Oil of Acorns drawn by the Retort, but it will be black, and of an ill Smell.
The Oak produces over and above the Acorn, the Misseltoe, and Polypody, a Moss which is what we call Usnea, and enters the Compositions of the Cyprus Powders; those of Frachipane and Le Mareshale, or the Farriers Powder, which we have brought from Montpellier. The true Description of making these Powders is unknown to me, which obliges me to refer the Reader to a Description made by the Sieur Barbe in a little Treatise of his printed at Lyons.