Sangstrom is trying to acquire some of the undetectable poison so that he can murder his wife. The hobbyist is pondering wether Sangstrom is worthy of the poison.
The hobbyist has just told Sangstrom that he has consumed the poison. And the antidote costs 1000 dollars and a written confession for his plot to kill his wife and the hobbyist for say he seeks revenge.
Sangstrom is annoyed at the hobbyist's treason and pulls out a gun. He does not shoot the hobbyist for fear he won't find the antidote. He agrees to pay 1000 dollars and writes a confession of his intention to murder of his wife for the hobbyist to use if he seeks revenge. Once this is mailed off to the hobbyist's friend, he receives the antidote.