In my research of early modern chemistry and medicine, I am currently focussing on the use of metals, particularly quicksilver. But other metals were also used widely, and the use of gold and silver is quite fascinating, in particular because it never disappeared entirely. In the late seventeenth century, silver was used to create aqua fortis or strong water, a kind of nitric acid. This was used to treat skin conditions, and to dissolve gold and make dyes. Silver was also used in medication that was supposed to strengthen the heart, but in 1747, Wouter van Lis refuted this: in his pharmaceutical handbook, he wrote that it is useless to add silver or gold to these drugs, as our body heat is incapable of solving them.
Van Lis had a point indeed: pure metallic silver and gold are not really toxic for the human body, as they are relatively resistant to corrosion by bodily processes. That is why eating small amounts of gold and silver leaf is harmless: European food additives E174 and E175 are simply silver and gold. This decorative use of precious metals was also familiar to Van Lis and his contemporaries: he noted that ‘…sometimes medication, like pills, is covered in silver or gold leave, to make it more pleasant to the eye.’ This covering was done in so-called pill silverers: spherical wooden containers on a small foot, into which silver or gold leave was put, moistened pills were added, and gentle swirling produced nicely silver or gold plated pills.
However, this innocuousness only goes for pure metallic precious metals, and not for compounds containing them, such as silver salts and colloidal silver. In the twentieth and twenty-first century, these have been advertised as a cure for a variety of ailments. They are sold as food supplements, thus avoiding the strict regulations that apply to medication. A sustained intake of these silver compounds can lead to argyria or silver poisoning. Although very rare and unlikely to interfere with vital functions, it gives the sufferer an irreversible bluish-silver hue. The most famous recent case is probably Paul Karason, an American man who turned permanently blue after taking large amounts of a home made silver compound to cure his arthritis. Probably not exactly the kind of silver lining you’re looking for in a cure…
 Bisschop, Jan. Pharmacia Galenica & chymica, dat is Apotheker ende alchymiste ofte distilleer-konste : begrĳpende de beginselen ende fondamenten der selver. Verdeylt in acht boecken, tot onderwĳsinge der apothekers / Door een liefhebber derselver konste Nieu licht der apotekers en distilleerkonst. Antwerpen: Reynier Sleghers, 1667. p.361-2 http://books.google.nl/books?id=MFRAAAAAcAAJ&printsec=frontcover&hl=nl&source=gbs_atb#v=onepage&q&f=false.
 Van Lis, Wouter. Gualtheri van Lis Pharmacopoea galeno-chemico-medica… = Meng- schei- … / Wouter van Lis Meng- schei- en geneeskonstige artseny-winkel. Amsterdam: Jan Morterre, 1747. p.103: “Het is vergeefs, dat Silver en Gout by Hartsterkende Geneesmiddelen gemengt worden, alzoze door onze warmte niet kunnen ontbonden worden, nochtans bekleet men zomtyts Geneesmiddelen, om ze voor het oog aangenamer te maken, By voorbeelt Pillen, met Silver of Blatgout.”
 White, J. M. L., Powell, A. M., Brady, K. and Russell-Jones, R. (2003), Severe generalized argyria secondary to ingestion of colloidal silver protein. Clinical and Experimental Dermatology, 28: 254–256. doi: 10.1046/j.1365-2230.2003.01214.x