"I was disgusted and angry. The pupil from whom I had hoped much had turned aside from the lofty heights of science to flirt with futilities, to dabble with the petty arts of the barber and the charlatan, the seller of poisoned gloves and poisoned handkerchiefs. "'It was a pity you did not live in Catherine's time,' I said to him once; 'you would have rivalled Cosme Ruggieri in her favour, and would have made a handsome fortune.' "'I fear I shall never grow rich by the transmutation of metals,' he answered. "After this he worked no more at toxicology, and seemed to resume his interest in my own particular studies. He was a man of remarkable intelligence, and had a specious art of appearing interested, which won my affection and sympathy. I know now that he was an infidel in science as in everything else, and that he only used my laboratory and my knowledge as a means of perfecting himself in the art of secret murder. Whether he studied poisons with the deliberate intent to use them at the first profitable occasion, or whether his dark soul delighted in the power to do evil, without the actual intention of crime, I know not; but I know that before he left my laboratory he had acquired by reading and experiment the most minute knowledge of poisons, and their effects and evidences. "About a week after that evening upon which Louis had seen my granddaughter at her harpsichord, my son told me with an air of triumph that the rich Mr. Topsparkle, the wealthiest Englishman who had ever visited Venice, had been to his shop, had looked at various examples of his workmanship, and had ordered a covered cup in parcel-gilt, set with agate and lapis-lazuli, after the manner of Cellini. My son took an artist's delight in the commission, and was almost indifferent to the profit which would be derived from his labour. "'He is quite a young man,' he told me, 'but he has a wonderful knowledge of the fine arts. I believe he knows every masterpiece of Cellini's; for while we were discussing the form of the cup which I am to make for him he drew at least twenty different forms of cups and covers, all after Cellini, with the most careless pencil. He is an excellent draughtsman, but music, he tells me, is his chief passion.' "A week later I was told that Mr. Topsparkle, having called to see the progress of his cup, had heard Margharita singing, and had asked to be introduced to the songstress. He had stayed for an hour listening to her, ravished by her talent. "Had I been a man of the world I should at once have taken alarm, remembering what I had heard in the coffee-house as to the Englishman's character. But I was too completely absorbed in my own studies to be on the alert for any danger that did not menace the secrets of my laboratory. I heard what had happened without being impressed by it.