Dear Dr. Bill: Incredibly there were legions of alchemists who worked extensively with mercury and lead in various forms (remember, the transmutation of lead to gold was a major goal of alchemy), and it seems they all labored merrily away for extended periods of time. In fact, drawings of the old experimenting alchemist with a long grey beard are stereotypical. But I wonder how long the average tenure of the occupation was, from the time they started experimenting until the heavy metals got to them in one way or the other...5 years, 10 years? less, more? Hmmm...there's a little trinket of data that you could research, Dr. Bill...must be available somewhere.