The Judge's powder?

In the court scene where Carton is defending Darnay who is accused of accused of treason, the judge keeps shaking some kind of powder in the air and on his desk. What is that?
First, I suspected it was perfume, but I've never seen it in a film and I thought they used to keep perfumes on handkerchiefs.
Then, I thought maybe it was something to dry ink, but he tosses it in the air(as well as on documents).
?