The alchemist was the forerunner of the modern chemist and, if science is defined as the search for knowledge, the alchemist has claims to being a medieval scientist. For his search was for the secret of turning base metals into gold, and also, by means of the mythical philosopher's stone, of achieving immortality. There were many honest alchemists who were sincere in their search for answers that eluded them but who, along the way, acquired a good deal of useful knowledge about the properties of metals and of acids.
    But there were also many dishonest charlatans who traded on the ignorance and credulity of the majority of the medieval population, to con them out of money they could ill afford.