This post made me curious.. What was in the anesthesia that was used in the 50's? It looks like the halothane was used in the 50's. Halothane contains fluroide and bromide.
The earliest anesthesias were ether and chloroform. Ether was abandoned because of its flammability. Chloroform was abandoned because of it's toxicity. Isoflurane is used today. It too contains bromide and fluoride.