Lewis and Clark took 50 dozen on their expedition.

“Rush’s pills,” otherwise known as “Thunderclappers,” combined calomel and jalap into an explosive cathartic. Calomel (six parts mercury to one part chlorine) was used as a purgative and jalap as a laxative. The depleting aspect of this medication was thought to rid the body of any “morbid” elements contained mainly in the blood.

These were called Thunderclappers for their effect. The L&C route has been traced by the excess of mercury in soil in places they stopped -- sometime, I think, for good reason!