Write on a paper, with a violet-coloured liquor, as many letters or words as you please, and ask any person which he will choose to have the writing, - yellow, green, or red. When he has made his choice, have a sponge ready with three sides, which you can easily distinguish, and dip each of its sides in one of the three sympathetic inks; then draw the side of the sponge which corresponds to the colour the person has chosen, over the writing, once only, and it will directly change to the colour required.

An Experiment with Sympathetic Ink, called the Oracular Letters.

Write on several slips of paper different questions, and such as may be answered by the name of some person: for example, Who is the merriest man in company? - Answer, Mr. ***. To whom will Miss *** be married? - Answer, To Mr. ***. These questions are to be written in the sympathetic ink of the fourth class, and exposed to the fire, and the answers written in the same ink, and left invisible. The papers are then to be folded in the form of letters, and in such a manner, that the part where the name is written shall be directly under the seal; in which case, the heat of the wax will make it visible. Then, if the letter be given to the person who requires the answer, he will find it plainly written.

An Experiment with Sympathetic Ink, called Winter changed to Spring.

Take a print which represents winter, and trace over the trees, plants, and ground, with the green sympathetic ink; observing to make some parts deeper than others, according to their distance. When those parts are dry, paint the other objects in their natural colours; then put the print into a glazed frame, and cover the back of it with a paper, pasted over its border only. When this print is exposed to the heat of a moderate fire, or to the warm rays of the sun, all the grass and foliage will turn to a pleasing green; and if a yellow tint be given to some parts of the print, before the sympathetic ink be drawn over it, the green will be of different shades, and the scene, that a minute before represented Winter, will now be changed into Spring. When this print is placed in the cold, Winter will appear again, and be again driven away by the warm rays of the sun; and this alternate change of seasons may be repeated as often as you please, provided the print be not made too hot.