At the time which we are now considering, it was not the custom, owing largely to the expensiveness of writing paper, to deliver to the pharmacist a written prescription. Instead, the physician first gave his instructions in person, and then, after he had seen the mixing and other steps of the apothecary’s work properly performed, he carried the preparation to the patient’s house. Long before the middle of the fifteenth century apothecaries had become thoroughly well established throughout Central and Western Europe. Among the statutes of the Medical Faculty of Erfurt, Germany, there has been found one which dates back to the year 1412 and which says:-- The student of medicine, before he applies for the Bachelor’s Degree, should spend one month in the spring of the year, in an apothecary’s establishment, in order that he may familiarize himself with the proper manner of preparing clysters, suppositories, pessaries, syrups, electuaries and other things necessary for a physician to know. The first work which was really worthy of being termed a treatise on materia medica was published in 1447. It bore the title, “Compendium Aromatariorum,” and was written by Saladin of Ascolo, the private physician of Prince Antonio de Balza Ossino of Tarentum. Berendes says that it was a work of much practical value. _The First Indications of the Beginning of Chemistry._--Up to a comparatively recent date it has been customary to speak of Geber as the first practical chemist and the first writer among the ancients who appreciated the important part which chemistry was likely to take in medicine and philosophy at no distant period of time. But to-day, as appears from the researches made by M. Berthelot about 1893, we are compelled to abandon the belief that such a person as Geber existed, and shall have to adopt the more commonplace view that the science of chemistry represents a gradual development from the much older alchemy. We may define the latter branch of knowledge as the science of transforming copper and brass into gold and silver. During the first two or three centuries of the Christian era there existed a firm belief that such a transformation had actually been accomplished, and in confirmation of the correctness of this statement it may be said that Zosimos of Panopolis, one of the leading philosophers of Alexandria during the fourth century of the present era, and a man who was considered by his contemporaries, as well as by all later alchemists, to be perhaps the greatest authority in this branch of knowledge, speaks in unmistakable terms in his cyclopaedic work on alchemy (28 volumes), of a certain tincture which possesses the power of changing silver into gold, and also of a “divine water” or fluid which is capable of effecting many different transmutations. There can therefore be no reasonable doubt that in the earlier centuries of the Middle Ages the learned men of Alexandria accepted alchemy as a well-established