Geraniums, except the shrubby kinds, require shelter from frost only, and should have free air admitted to them, when the weather is not very severe. In sultry weather, they should all be watered liberally every morning, except some few of a succulent nature, which must be watered sparingly; the latter may be known by plucking a leaf from them. Geraniums may be watered three times a week, when not frosty, in winter. 724. _Artificial Mould for Plants._--Russian potash, one drachm; water, four ounces; one tea-spoonful of oil. Mix the whole well together. Seeds put in this mixture will grow for a time at least, as well as if planted in common soil. 725. _To take Impressions of Plants._--Take half a sheet of fine paper, and cover the surface with sweet oil; let it stand a minute or two, then rub off the superficial oil, and hang the paper in the air; when almost dry, move the paper slowly over the flame of a candle or lamp, till it is perfectly black; lay on it the plant or leaf, place a piece of clean paper over, and rub it equally with the fingers for half a minute. Then place the plant on the paper or scrap-book where it is desired to have the impression, cover it with blotting paper, and, on repeating the rubbing, a representation of the plant will appear equal to the finest engraving. The same piece of black paper will serve for a number of impressions. 726. _Another Process._--Burn a common cork till reduced to powder; mix with it a tea-spoonful of olive oil, making a thick paste. Paint the veiny side of the leaf with a camel-hair brush, and lay it, with the painted side down, on a piece of clean paper. Submit it to a strong and even pressure (it is best placed in a book and put under a weight,) for about fifteen minutes; remove the leaf carefully, and there will be an exact representation left. Very veiny leaves are best. These impressions are almost equal to engravings. Collections of them might be made interesting, by having narratives of rambles written under them, stating the features of the spot from which the leaves were gathered. DIRECTIONS FOR WINDOW-PLANTS.