Still another idea in a single slate is as follows: An ordinary looking slate is given out for examination, and, on its being returned to the medium, he takes his handkerchief and cleans or brushes both sides of the slate with it; and, upon again showing that side of the slate first cleaned, it is found covered with writing apparently done with chalk. The following is the simple explanation of it: Take a small camel’s hair brush and dip it in urine or onion juice, and with it write or trace on the slate whatever you desire, and when it becomes dry, or nearly so, the slate can be given for examination without fear of detection. The handkerchief the performer uses to clean the slate with is lightly sprinkled with powdered chalk. He makes believe to clean the one side devoid of preparation, but the side containing the invisible writing is gently rubbed with the handkerchief, not too hard just enough to let the powdered chalk fall on the urine or onion juice, where it leaves a mark not unlike a chalk mark. It will not be out of place to describe a trick by which writing is produced upon an ordinary china plate by a somewhat similar means. The plate is examined and cleaned with a borrowed handkerchief, and then the performer requests the loan of a pinch of snuff, or uses a little sand or dust, which he places on the plate. He now commences to move the plate around in circles, and while doing so the snuff or sand is seen to gradually form itself into writing. The explanation is simple--whatever writing you desire to appear on the plate is placed beforehand on it. It is done with a camel’s hair brush dipped in the white of an egg and allowed to become dry before being handed around for inspection. As the performer cleans the plate he breathes on both sides of it, as if to give it moisture enough to help take off any dirt that might be thereon when rubbed with the handkerchief. In breathing on the front of the plate containing the writing done with the white of the egg, he moistens the writing enough to make the snuff or sand, as the case may be, adhere to it. Of course, in cleaning the front of the plate, care must be taken not to brush or disturb the invisible writing.