The Great Keinplatz Experiment

The Great Keinplatz Experiment is a short story written by Arthur Conan Doyle first published in the Belgravia magazine in july 1885.
This is the first fiction dealing with spirits. 30 years before his active involvement for the spiritualism cause.
Professor von Baumgarten, an expert about mesmerism and spirits, is convinced that the spirit of hypnotized people can leave the body, travel around and come back at will. But there is one problem, the spirit can't be seen and no evidence can be given...