Under these conditions, then, it was hardly conceivable that a manifestation which depends, in its initial stages, upon the most delicate of vibrations--the unknown vibrations of the psychoplasm could take place. Truth is dependent upon experiment, upon patient repetition and trial and error. In order to test the theory in actual practice, I determined to pay a visit to the well-known and malignant ghost at X----[19] and actually put to the test whether or not a ghost can manifest in the presence of a radium salt. The rays of radioactive salts are unable to pass through lead, and pure radium bromide, which is the nearest that we have got to the isolation of the element radium, always has to be kept in a leaden box or cell, as otherwise its rays would pass through and destroy the skin and flesh of the man carrying it. Before the properties of radium were known, this destructive faculty of radium vibrations caused several mishaps, for unwary men of science carried these dangerous salts loose in glass vials in their pockets. For the purposes of experiment I obtained the loan of a small supply of a solution of a radium salt that gives out powerful emanations. This was enclosed in a glass vial which was in turn encased in a leaden box. The haunted house is a peculiar old building of no particular architectural beauty. It stands remote and deserted in its own overgrown extended grounds, and over it breathes a generally depressing atmosphere of damp, neglect, oppression, and decay. Viewed from the outside the house presents no outstanding features that attract the eye. The lower windows are heavily barred by rusted iron rails without and closed wooden shutters within. Even creepers seem to have felt the blight that lies upon the mansion, for no patch of green or rambling ivy tendril covers the bare surface of the brick. Three storeys high, mansard-roofed and turreted with a dozen contorted Tudor chimney-stacks, the roof-line stands out against the sky and the dull leaf masses of the surrounding trees. The higher windows are also shuttered, but not even the small boys of the neighbouring village have dared to break the grimy window frames that lie over the shutters. Desolate and forbidding, the mansion and its grounds lie derelict, shunned by all men. My key is that of the small back door, and it is used but once or twice a year when the needs of the psychic call upon us to tread a path of peril and hazard. Inside one steps into the cold stone-flagged passages that lead to the empty kitchens and offices. The air is heavy and dank with that queer smell of earth that one associates with crypts and graves rather than with the clean new-turned furrow. The whole house is bare of furniture, the paint of the woodwork dull and dirty. Spots of amorphous fungus cling to the walls, and here and there wallpaper has peeled off in long leprous strips, exposing the corpse-grey plaster behind.