Lewis & Clark left a trail of mercury-laden poop

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In lieu of a trained physician, the Corps of Discovery’s leaders got some basic medical training, along with a bag full of the tools of allopathic intervention: lancets for bleeding patients, blister powder for inducing “heat,” opium products for relieving pain and inducing sleep — and purgatives.

Those purgatives are the heroes of our story today. They came in the form of beefy pills, about four times the size of a standard aspirin tablet, which Rush called “Dr. Rush’s Bilious Pills.” They contained about 10 grains of calomel and 10 to 15 grains of jalap.

Jalap, the powdered root of a Mexican variety of morning glory, is a natural laxative of considerable power.

And calomel ... ah, calomel. Calomel was the wonder drug of the age. Its chemical name is mercury chloride. In large doses (and they don’t get much larger than 10 grains, especially if a fellow takes two of them, as Dr. Rush recommended!) it functions as a savage purgative, causing lengthy and productive sessions in the outhouse and leaving a patient thoroughly depleted and hopefully in full restoration of his bile balance.

Calomel also was the only thing known to be effective against syphilis, which was always an issue with military outfits. Whether picked up from a friendly lady in a waterfront St. Louis “sporting house” before the journey, or from an equally friendly Native lady met along the way, syphilis went with soldiers like ice cold milk with an Oreo cookie.

When symptoms broke out, the patient would be dosed with “thunder clappers” and slathered with topical mercury ointments until he started salivating ferociously, which was a symptom of mild mercury poisoning but at the time was considered a sure sign that the body was purging the sickness out of itself.

And yes, a few of the men did end up needing treatment for syphilis. But everyone in the party needed a good laxative on the regular (sorry about that). Week after week, hunting parties went out and brought back animals to eat. The explorers lived on almost nothing but meat.

And this low-fiber diet had predictable results.

It had another result, too, which was less predictable — although highly convenient for later historians. The fact is, mercury chloride is only slightly soluble in human digestion. Plus, the reason it works is, it irritates the tissues of the digestive tract severely, causing the body to expel it just as fast as it possibly can before more damage can be done. So, most of the calomel in any given “bilious pill” gets blown out post-haste in the ensuing “purge.”

Then, once out of the body and in the earth, it lasts literally for centuries without breaking down or dissolving away.

So as Lewis and Clark and their crew made their way across the continent, and across Oregon, they were unknowingly depositing a trail of heavy-metal laxatives along the way — a trail that historians and scientists have been able to detect and use to document almost their every, uh, movement.

(Sources: Class lecture in History of American Medicine, October 2009, Univ. of Oregon; Or Perish in the Attempt: Wilderness Medicine in the Lewis and Clark Expedition, a book by David J. Peck published in 2002 by Farcountry Press; “Following Lewis and Clark’s Trail of Mercurial Laxatives,” an article by Marisa Sloan published in the Jan. 29, 2022, issue of Discover Magazine.)

Finn J.D. John teaches at Oregon State University and writes about odd tidbits of Oregon history. His most recent book, Bad Ideas and Horrible People of Old Oregon, published by Ouragan House last year. To contact him or suggest a topic: finn@offbeatoregon.com or 541-357-2222.