Another medium employed a somewhat similar method, only the paper in this case was placed in a glass vial (Fig. 5) which had been lying on the iron trap door. The medium’s hand covered the vial, which was corked and sealed, while the writing was making its appearance. You can also produce writing on the paper in the vial without resorting to the use of heat by using a vial that has been washed out with ammonia and kept well corked, and writing on the paper with a weak solution of copper sulphate, which is invisible until the paper is placed in the vial, when the two chemicals produce writing in blue. Still another message is produced as follows: The writing is done with iron sulphate on blank cards. Of course this is invisible. These cards are placed in envelopes and sealed up. Upon opening the envelopes shortly afterward the cards are covered with the writing which was before invisible, but is brought out by a solution of nut galls with which the inside of the envelopes had been slightly moistened. The subject of sympathetic inks is such an interesting one that we give thirty-seven formulas, which include all those which are liable to be used by the medium. The solutions used should be so nearly colorless that the writing cannot be seen till the agent is applied to render it visible. Sympathetic inks are of three general classes. _Inks that Appear through Heat._ 1. Write with a concentrated solution of caustic potash. The writing will appear when the paper is submitted to strong heat. 2. Write with a solution of ammonium hydrochlorate, in the proportion of 15 parts to 100. The writing will appear when the paper is heated by holding it over a stove or by passing a hot smoothing iron over it. 3. A weak solution of copper nitrate gives an invisible writing, which becomes red through heat. 4. A very dilute solution of copper perchloride gives invisible characters that become yellow through heat. 5. A slightly alcoholic solution of copper bromide gives perfectly invisible characters which are made apparent by a gentle heat, and which disappear again through cold. 6. Write upon rose colored paper with a solution of cobalt chloride. The invisible writing will become blue through heat, and will disappear on cooling. 7. Write with a solution of sulphuric acid. The characters will appear in black through heat. This ink has the disadvantage of destroying the paper. (See the caution given on page 9.) 8. Write with lemon, onion, leek, cabbage or artichoke juice. Characters written with these juices become very visible when the paper is heated.