A Story of Mercury

Mercury and Early Felt Hat Manufacturing

A 19th Century Map of the Arch Street Project excavation site reveals that a felt hat factory was later built on top of part of the original cemetery.  The map cites the owner as “P. Hirst and son”. Subsequent archival research by the team’s principle historian, Nick Bonneau, has revealed that the hat factory owner was actually P. Herst and that the factory only existed at the site for 16 years (1872-1887).  In the 19th century “Stetson-style” felt hats were very popular. The felt used to make these hats was produced from small animal pelts. During the 19th century, fur was removed from the animal skin using camel urine, though some hatters used their own urine, instead. The active ingredient in urine is nitrogen-rich urea. Interestingly, those hatters who used their own urine and were being treated for syphilis produced superior felt! This was due to the mercurous chloride (HgCl) they had taken as medicine.

Mercury and Syphilis

Syphilis was frequently treated with mercuric chloride before the advent of antibiotics. It was inhaled, ingested, injected, and applied topically. Both mercuric-chloride treatment for syphilis and poisoning during the course of treatment were so common that the latter's symptoms were often confused with those of syphilis.  Urine was eventually replaced in the 19th century hat making process by orange-colored mercuric nitrate Hg(NO₃)₂. The vats of solution and the drying process generated dangerous levels of mercury fumes which were a source of chronic poisoning in hat makers during this era. Chronic mercury poisoning leads to tremors, mood disorders, and dementia. Victims were called “mad hatters.”  The Mad Hatter is one of the best known characters in Lewis Carroll’s Alice in Wonderland.

Without treatment with antibiotics, syphilis could lie dormant (sometimes for many years), only to reappear. Today, doctors  see only a handful of untreated syphilis but in the 19th century, it was common. The symptoms of untreated, advanced syphilis (also known as tertiary syphilis) was nothing short of horrific. Some tertiary syphilitics developed acute cardiovascular disease and succumbed to an aneurysm. Others developed necrotic facial gummas, in which cranial bone and cartilage disintegrated. Less common, but no less destructive, is neurosyphilis, in which the central nervous system breaks down. Many syphilis sufferers in the 19th century ended their days in asylums, where their  mercury-treated symptoms, including personality changes, hallucinations, incontinence, sexual dysfunction and seizures, could only be managed, not cured.

Testing For Mercury in the Arch Street Project Soil

Recently we tested some of the soil from the coffins of bodies excavated near the site of the former hat maker for mercury. Preliminary results reveal that the majority of the soil  samples contained no mercury. This means that either there was no mercury released from the hat factory into the soil or if there was any mercury released from the hat factory into the soil, it did not make it into these graves. One grave (G-262) of an adult male, however, did show elevated levels of mercury.  This observation raises the possibility that this individual might have taken mercury as a medicine prior to his death for an ailment such as syphilis. Today syphilis can be effectively treated using various forms of the antibiotic penicillin. Penicillin would not have helped anyone who suffered from syphilis buried at the Arch Street site in the eighteenth and nineteenth century as it was not available commercially until 1942 in the United States.