Scottish obstetrician, James Young Simpson, communicated to the Medico-Chirurgical Society of Edinburgh meeting on November 10, 1847 his human anaesthetising experiments using chloroform, which he published as an “Account of a New Anaesthetic Agent as a Substitute for Sulphuric Ether in Surgery and Midwifery“. Simpson and his two assistants on the evening of November 4, 1847, lost consciousness after purposely inhaling chloroform, he then used it during childbirth. Within weeks of its appearance, chloroform had almost completely replaced ether as the standard anaesthetic. [1, 2, 3, 4]
In 1867 Joseph Lister’s discovered of the “antiseptic principle“, which jointly, these discoveries opened the path for general medical surgery – “solving” the problems pain and infection. I suspect it helped spur on animal experimentation also.
Chloroform had been invented in 1831 “made by reacting acetone with chlorine”, in 1842 it was tried as an anaesthetic on animals by Dr Robert Mortimer Glover, he deemed it too dangerous for humans.