"Within fifteen minutes? How do you know?" cried Jim.
"It is written here, in the book."
"And where would Jean Cladel have learnt to handle the paste with safety, how to prepare the solution?" Jim went on.
"Here! Here! Here!" answered Hanaud, tapping with his knuckles upon the treatise. "It is all written out here—experiment after experiment made upon living animals and the action of the poison measured and registered by minutes. Oh, given a man with a working knowledge of chemicals such as Jean Cladel must possess, and the result is certain."
Betty Harlowe leaned forward again over the book and Hanaud turned it half round between them, so that both, by craning their heads, could read. He turned the pages back to the beginning and passed them quickly in review.
"See, Mademoiselle, the time tables. Strophanthus constricts the muscles of the heart like digitalis, only much more violently, much more swiftly. See the contractions of the heart noted down minute after minute, until the moment of death and all—here is the irony!—so that by means of these experiments, the poison may be transformed into a medicine and the weapon of death become an agent of life—as in good hands, it has happened." Hanaud leaned back and contemplated Betty Harlowe between his half-closed eyes. "That is wonderful, Mademoiselle. What do you think?"
Betty slowly closed the book.
"I think, Monsieur Hanaud," she said, "it is no less wonderful that you should have studied this book so thoroughly during the half-hour you waited for us here this morning."
It was Hanaud's turn to change colour. The blood mounted into his face. He was for a second or two quite disconcerted. Jim once more had a glimpse of the secret duel and rejoiced that this time it was Hanaud, the great Hanaud, who was scratched.
"The study of poisons is particularly my work," he answered shortly. "Even at the Sûrété we have to specialise nowadays," and he turned rather quickly towards Frobisher. "You are thoughtful, Monsieur?"