[1] _Method of preparing jet powder._
Pound in a copper mortar your jet, which must have been bruised a
little with a hammer; when it is well pounded, it must be sifted
through a sieve, and also through a piece of muslin. Keep that powder,
which cannot be too fine, in a little box, to use it when occasion may
require: take a pinch of it either with your fingers or with a piece
of paper; then scatter it on the card, and it will stick only in those
places that have been touched by the roll of pomatum, and may be taken
off very easily by the rubbing against the carpet, when you will push
the hand of the person who covers the card, without the card being
soiled in the least by it.