Chloroform

Chloroform is the organic compound with formula CHCl3. This colorless, sweet-smelling, dense liquid is a trihalomethane.

Chloroform was discovered in July, 1831 by the American physician Samuel Guthrie, and independently a few months later by the French chemist Eugène Soubeiran and Justus von Liebig in Germany. It was mainly used as an anesthetic. Inhaling chloroform vapors depresses the central nervous system of a patient, causing dizziness, fatigue and unconsciousness, allowing a doctor to perform simple surgery or various, otherwise painful, operations.

Chloroform in "The Haunted Bicuspid"
In 1851 William Legrand had a bicuspid extracted with the help of chloroform. On previous visits to dentists, he had tried to drink himself blind first to dull the pain. Or he would take so much opium he could not recollect his name. On one occasion, he tried both at once. Nothing helped and so he considered Vankirk's suggestion of chloroform a humbug. But it was no humbug, in fact it was a sockdolager.