From : BBC World News By : Jasmin Fox-Skelly Edited by : Amal Udawatta BBC/ Serenity Strull/ Getty Images How general anaesthetics work is still not fully understood, but they are revealing clues about the nature of consciousness. In 1797, the British naval commander Admiral Horatio Nelson had his right arm amputated. The operation saved his life. But according to legend the only anaesthetic he was offered was a swig of rum . For the majority of human history, even the removal of limbs was done on patie...