If doubts and difficulties envelope the discovery of poisons, whose distinguishing character is the rapidity of these effects, how much greater must be the uncertainty when we are required to ascertain the administrations of what are called slow poisons. This subject, indeed, is so closely entwined with popular superstitions, that it is difficult to separate truth from falsehood. In Italy, for example, it was formerly said, that poisons were made to destroy life at any stated period--from a few hows to a year. This, however, turns out to be a mere fiction; and, it is well understood, that we know of no substances that will produce death at a determinate epoch. The following case of the late Prince Charles of Augustenburgh, nevertheless, shows that the idea of slow poison is still very prevalent, even among the physicians of continental Europe. Prince Charles of Augustenburgh, Crown Prince of Sweden, and the predecessor of Bernadotte, in that station, fell dead from his horse on the 22nd of May, 1810, while reviewing troops in Scania. His death, during that stormy period of public affairs, excited great attention, and an opinion soon spread abroad that he had been poisoned. The king ordered a judicial investigation; and it appeared that Dr. Rossi, the physician of the late Prince, had, without directions, proceeded to inspect the body twenty-four hours after death; that he had performed this operation with great negligence, omitting many things which the law presented, which the assisting physicians proposed, and which were essential to render it satisfactory; and finally, that the coats of the stomach, instead of being preserved and submitted to chemical analysis were, according to his own acknowledgment, thrown away. The royal tribunal adjudged him to be deprived of his appointment, and to be banished from the kingdom. This decision would not of course, diminish the suspicion already excited; and among other physicians, who were consulted on the case, M. Lodin, professor of Medicine at Lynkoping, presented two memoirs, in which he stated it as his opinion, that a _slow poison_ of a vegetable nature, and probably analogous to the _aqua tofania_, had been administered to the Prince, and that this had caused the apopletic fit of which he died. His reasons were: 1. That the Prince had always enjoyed good health previous to his arrival in Sweden, and, indeed, had not been ill, until after eating a cold pie at an inn, in Italy. He was shortly after seized with violent vomiting, while the rest of the company experienced no ill effects. 2. The Prince was naturally very temperate. 3. Ever since he arrived in Sweden he had experienced a loss of appetite, with cholic and diarrhoea; and