(1) L. M. W. asks (1) a receipt for marsh mallows, as made by confectioners. A. Dissolve one-half pound of gum arabic in one pint of water, strain and add one half pound of fine sugar, and place over the fire, stirring constantly until the sirup is dissolved, and all of the consistency of honey. Add gradually the whites of four eggs well beaten. Stir the mixture until it becomes somewhat thin and does not adhere to the finger. Flavor to taste and pour into a tin slightly dusted with powdered starch, and when cool divide into small squares. 2. The title of a good veterinary journal. A. _American Veterinary Review_, New York. 3. The formula for a spavin cure? A. Take of sweet oil 4 ounces, spirits of turpentine 2 ounces, oil of stone 1 ounce. Mix and apply three times per day. 4. A receipt for a wash that will prevent rabbits from injuring the bark of fruit trees. A. We know of nothing good for this purpose. (2) A. L. K. asks how common fat can be rendered into tallow in an open kettle. A. Keep the tallow melted for some time, along with about two per cent of sulphuric acid largely diluted with water, employing constant agitation, and allowing the whole to cool slowly; then remelt the cake with a large quantity of hot water, and wash well. (3) W. C. B. asks about the process and kind of machinery used in preparing raw sienna for paint. A. The raw sienna is thrown directly on the hearth of a reverberatory furnace and kept thoroughly raked until it assumes a proper color. Very little, if any, sienna is known to be burnt in this country. (4) W. M. M. asks for some transparent paint suitable to paint on tracing muslin. A. You must use a transparent varnish such as the following: Dissolve 30 parts of copal and 2 parts of camphor in 120 parts of oil of turpentine and 30 parts of oil of lavender. Use lakes, gamboge, Prussian blue, and the other transparent colors, mixed with the vehicle. (5) S. S. asks a receipt for black heads. A. Cover the parts afflicted with a pomade consisting of kaolin 4 parts, glycerine 3 parts, acetic acid 2 parts, with the addition of a small quantity of ethereal oil. See SUPPLEMENT, No. 542. (6) W. L. asks (1) a cure for frost bitten feet. A. For frost bites, rub the affected parts with pure oil of peppermint. It will also prevent the after effect of chilblains. Care should be taken to use only the pure oil, and not the essence of peppermint, as the essence will not have the desired effect. 2. How plate glass is made. A. See SCIENTIFIC AMERICAN SUPPLEMENT, No. 340. (7) A. T.--Hard rubber is a very good insulator; gutta percha is also very good, and can be softened by boiling water and given any desired shape.