Silver and Medicine
In the Museum of the Order of St John, you can see a collection of silver displayed in the Old Chancery. While the shining cabinets reflect the wealth of the religious Order of St John in the 18th and 19th centuries, a tour guide might tell you an interesting story about the use of silver plates in the original St John Hospital in Jerusalem, after which the order was founded in 1113. In this hospital, patients were treated as if they could be the next coming of Christ, and served from silver platters. It is now known that this use of silver was important in keeping infection and cross contamination levels down in the hospital and inadvertently protecting the patients.
Pirates were said to pierce their ears with silver or gold in order to improve the eyesight of the corresponding eye to ear, and while this technique seems to have no scientific explanation, the practice of putting silver coins into the drinking water aboard ships does. Silver has antimicrobial properties, meaning it will aid in the breakdown of bacteria, helping to keep things like water free of contaminants. On land, the same technique was used. The ancient Phoenicians, Greeks, Romans, Egyptians,and others also were recorded to have used silver in one form or another to preserve food and water, which was especially important on long journeys or on the battlefield. Silver was still used extensively for this purpose throughout World War II.
In Rome in 69 B.C.E., silver nitrate was mentioned in a pharmacopeia as a medical agent, and has been used and refined throughout history in a number of ways. The most common and successful of these uses was as a support to heal wounds, while the least effective was its use to treat ill understood brain and mental health difficulties, see more about this in Silver and the Moon.
By 1800, it was widely known and understood that wine, water and milk stayed pure for longer if kept in silver bottles. By this time the use of silver nitrate to treat skin ulcers and aid in healing wounds was also widely known and understood to be because the metal aided in the breakdown of bacteria (which is important, as antibiotics as we know them now were not discovered until the end of the century).
Today, you will find silver nitrate in plasters and wound dressings, but you might also find information online about 'colloidal silver' being used as a kind of cure-all. The medical use of colloidal silver (which is ingested rather than applied to any kind of wound) is not proven, and is the kind of practice which can result in Argyria, see Silver and Class for more info.
While piercing your ear might not really improve your eyesight, the mythical protective powers of silver remain today - and presumably grew from its incredible power to purify water and keep people from becoming ill on long journeys or after sustaining dangerous wounds.