It may not be amiss to also mention another method of producing writing, employed by mediums to obtain a message on a blank piece of paper which has been placed between two slates, which are held by the medium in his hand, high above his head, and, on afterwards taking the slate apart, the paper is covered with writing. This again calls into use the extra or false flap. (Fig. 1.) A piece of paper with writing on it is placed face downward on one of the slates and covered with the false flap. It then looks like an ordinary slate. On this is placed the plain piece of paper, and over this is laid the second slate. The slates are now held up in plain view of the audience, and on being lowered to the table they are turned over, thus bringing the blank piece of paper under the false flap and the one with the writing on it on the top of the flap, which has fallen from the slate, which is now the top, but originally the bottom one, on or into the under one, and, of course, on the removal of the present top slate, the writing is found on what is supposed to be the original blank paper. [Illustration: Fig. 4.--False Table for Developing Communications Written with Sympathetic Ink.] If the paper is to have a private mark put on it by an observer, so as to prove the writing really does appear on that identical piece of paper, the operation is varied as follows: The false flap is done away with, and the paper, which is furnished by the medium, has written on it the desired communication with ink, which is made visible and brought out black by means of heat. For the invisible ink you can use sulphuric acid, very much diluted, so as not to destroy the paper. The necessary heat is obtained in the following manner: The table (Fig. 4) on which the slates are resting is hollow, and has concealed in it a spirit lamp filled with alcohol. This lamp sits directly under a trap in the table top, which is covered underneath for safety with sheet iron, so it will not catch fire. When the slates are placed on the table they are laid over the little trap door, which, in conjuring parlance, is known as a “trap.” This is now opened, and the slates allowed to become well heated and the trap then closed, and the prepared paper, upon coming in contact with the hot slate, is thus covered with writing. [Illustration: Fig. 5.--The Development of Spirit Writing.]