John Ching patented a medicine for “destroying worms” on July 11, 1796. The two types of lozenges, brown and yellow, were for morning and night respectively (Operative Chymist, 1997). Sold until the 1860s, both contained mercury.
Here is a recipe (The Family Oracle of Health: Economy, Medicine, and Good Living, 1824)
To read about a child’s death from and the father’s campaign against these lozenges: http://thequackdoctor.com/index.php/the-tragic-story-of-chings-worm-lozenges/