“It is strange to reflect,” said Kalmon, looking at the tube thoughtfully, “that one of those little things would be enough to put a Hercules out of misery, without leaving the slightest trace which science could discover.”

Corbario was still shading his eyes from the light.

“How would one die if one took it?” asked Aurora.  “Very suddenly?”

“I call it the sleeping death,” answered the Professor.  “The poisoned person sinks into a sweet sleep in a few minutes, smiling as if enjoying the most delightful dreams.”

“And one never wakes up?” inquired Marcello.

“Never.  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.  I have made enough to send all our thirty-three millions of Italians to sleep for ever!”

Kalmon laughed pleasantly.

“If this could be properly used, civilisation would make a gigantic stride,” he added.  “In war, for instance, how infinitely pleasanter and more aesthetic it would be to send the enemy to sleep, with the most delightful dreams, never to wake again, than to tear people to pieces with artillery and rifle bullets, and to blow up ships with hundreds of poor devils on board, who are torn limb from limb by the explosion.”

“The difficulty,” observed the Contessa, “would be to induce the enemy to take your poison quietly.  What if the enemy objected?”

“I should put it into their water supply,” said Kalmon.

“Poison the water!” cried the Signora Corbario.  “How barbarous!”

“Much less barbarous than shedding oceans of blood.  Only think—­they would all go to sleep.  That would be all.”

[Illustration:  “‘I call it the sleeping death,’ answered the professor”]

“I thought,” said Corbario, almost carelessly, “that there was no longer any such thing as a poison that left no traces or signs.  Can you not generally detect vegetable poisons by the mode of death?”