Lewisite

Much of the testing involved mustard gas, arsenic, and other well-established poisons.

But also in DC at the same time was a man named Winford Lee Lewis, whose name would be attached to a brand-new invention, a compound called lewisite.

Lewisite was developed after a student combined arsenic trichloride and acetylene, producing a foul-smelling black tar.

When the student smelled the substance, he became immediately sick and was sent to a hospital, where it took days to recover.

Winford Lee Lewis later perfected this compound, making a solution that smelled of geraniums, but was incredibly deadly.