It is impossible, I believe.

I have made experiments on animals, and have not succeeded in waking them by any known means." "I suppose it congests the brain, like opium," observed Corbario, quietly.
"Not at all, not at all!" answered Kalmon, looking benevolently at the little tube which contained his discovery.

"I tell you it leaves no trace whatever, not even as much as is left by death from an electric current.

And it has no taste, no smell,--it seems the most innocent stuff in the world." Corbario's hand again lay on the table and he was gazing out into the night, as if he were curious about the weather.

The moon was just rising, being past the full.
"Is that all you have of the poison ?" he asked in an idle tone.
"Oh, no! This is only a small supply which I carry with me for experiments.