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.
A remarkable Experiment, called the Revivified Rose.
Take a rose that is quite faded, and throw in some common sulphur in a chafing-dish of hot coal. Hold the rose over the fumes, and it will become quite white; then dip it into a basin of water, and giving it to any one, tell him to put it into his box or drawer, and after locking it, to give you the key. About five or six hours afterwards, return him the key, and when he unlocks his drawer, instead of the white rose he put into it, he will find one perfectly red.
How to Write on Glass by means of the Rays of the Sun.
Dissolve chalk in aqua-fortis, to the consistence of milk, and add to it a strong solution of silver; keep this liquor in a glass decanter, well stopped, and cutting out from a paper the letters you wish to appear, paste it on the decanter, and place it in the sun, in such a manner, that its rays may pass through the spaces cut out of the paper, and fall on the surface of the liquor; then will that part of the glass through which the rays pass be turned black, while that under the paper will remain white; but particular care must be taken that the bottle be not moved during the time of the operation.
To produce different Colours, by pouring a colourless Liquor into a clean Glass.