What does Sydney purchase after walking Mr. Lorry to the Manette’s? (From Book 3 Chapters 6-10)

Sydney Carton purchases certain types of drugs from the chemist. He gives the chemist a list, but we are not apprised of exactly what is procured in the small packets.

".... he stopped at a chemist's shop, which the owner was closing with his own hands. A small, dim, crooked shop, kept in a tortuous, up-hill thoroughfare, by a small, dim, crooked man.

Giving this citizen, too, good night, as he confronted him at his counter, he laid the scrap of paper before him. "Whew!" the chemist whistled softly, as he read it. "Hi! hi! hi!"

Sydney Carton took no heed, and the chemist said:

"For you, citizen?"

"For me."

"You will be careful to keep them separate, citizen? You know the consequences of mixing them?"

"Perfectly."

Certain small packets were made and given to him. He put them, one by one, in the breast of his inner coat, counted out the money for them, and deliberately left the shop.