35. To Write Black Characters with Water.--Mix 10 parts nutgalls, 2½ parts calcined iron sulphate. Dry thoroughly, and reduce to fine powder. Rub this powder over the surface of the paper, and force into the pores by powerful pressure, brush off the loose powder. A pen dipped in water will write black on paper thus treated. 36. To Write Blue Characters with Water.--Mix iron sesquisulphate and potassium ferrocyanide. Prepare the paper in the same manner as for writing black characters with water. Write with water, and the characters will appear blue. 37. To Produce Brown Writing with Water.--Mix copper sulphate and potassium ferrocyanide. Prepare the paper in the same manner as before. The characters written with water will be reddish brown. Here is another trick calling for the use of sympathetic ink. A medium suggests a number of questions to write on a paper, one of which you select and write on a slip of paper furnished by the medium. Writing is done with pen and ink. You are requested to dry it with a blotter, and not to remove the blotter for a time, the medium says, so as to keep the paper in the dark, thus giving the “spirits” better conditions under which to work. After a while the blotter is removed, and an answer to the question is found on the same paper. The questions suggested were all of such a character that one answer would nearly do for any one. The paper the question was written on had this answer written with invisible ink brought out by a reagent on the blotter, with which it was saturated, and thus another mystery is easily dispelled. We will now take up a few slate tests, in which the slates are brought or furnished by the spectator or investigator. The tests in which the slates are brought by skeptics and tied and sealed by them, and still writing is obtained upon them, are the ones that are the most convincing and most talked about, and they are offered to the unbeliever as proof absolute of spirit power. [Illustration: Fig. 6.--Writing on the Slate with the Pencil Thimble.]