One possible explanation is that Twain was relating it to Salpetriere Hospital in Paris -- a former gunpowder factory (saltpeter is a component of gunpowder.) "Stirring Times in Austria" was written at a time when Twain was pondering theories of the mind. French neurologist Jean-Martin Charcot was associated with the Salpetriere and Twain has indicated he was familiar with the French experiments. Although she does not mention "Stirring Times in Austria," Susan Gillman discusses Twain's interest in Charcot's work in _Dark Twins: Imposture and Identity in Mark Twain's America_. Barb