Take a print that represents winter, and colour those parts which should appear green, with the second green invisible ink, described in page 25; observing, of course, the usual rules of perspective, by making the near parts deeper in colour than the others. The other objects must be painted in their natural colours. Then put the print into a frame with a glass, and cover the back with a paper that is pasted only at its extremities. When this print is exposed to a moderate fire, or the warm sun, the foliage, which appeared covered with snow, will change to a pleasing green; and if a yellow tint be thrown on the lighter parts before the invisible ink is drawn over it, this green will be of different shades. When it is exposed to the cold, it will again resume its first appearance of winter. _The Silver Tree._ Dissolve an ounce of fine silver in three ounces of strong aqua fortis, in a glass bottle. When the silver is dissolved; pour the aqua fortis into another glass vessel, (a decanter will be best,) with seven or eight ounces of mercury, to which add a quart of common water; to the whole add your dissolved silver, and let it remain untouched. In a few days the mercury will appear covered with a number of little branches of a silver colour. This appearance will increase for a month or two, and will remain after the mercury is entirely dissolved. _The Lead Tree._ A more modern invention, and an easier method by far than the above, is the following: To a piece of zinc fasten a wire, crooked in the form of the worm of a still; let the other end of the worm be thrust through a cork. You then pour spring water into a phial or decanter, to which you add a small quantity of sugar of lead; thrust the zinc into the bottle, and with the cork at the end of the wire fasten it up. In a few days the tree will begin to grow, and produce a most beautiful effect. _To produce beautiful Fire-works in Miniature._