S. N., of N. Y.—Sand is less fusible than iron, therefore it requires a higher temperature to melt it. Sand radiates the heat imparted to it more slowly than iron. It would not answer for lining the inside and outside of stoves. Fire-brick is far superior to it for inside lining, and soapatone for the outside coating. Iron is a good conductor; sand ia classed among the non-conduc-tora of heat. T. M. B., of Pa.—Any work on photography will instruct you how to prepare paper for taking impressions by the camera obscura. T. C, of Pa.—Air baga or buoys have been attached to the Atlantic telegraph cable, and found not; tu answer. J. J. W., of 111.—H. C. Baird, of Philadelphia, is publisher of a work called the "Practical Distiller," which ivill give you the information desired regarding domes! ic liquors. H. It., of Ky.—The following is a safe ami excellent recipe for tooth powder : Fine chalk, 2 orniez, powdered cuttle fish,2 ounces,andpowderedorriroot, 1 ounce, Mk all together, and use at night before retiring. II. P. I*, of Conn.—Iron pipe is not only cheaper than lead, but much healthier, especially tor conveying water to be used for domestic purpose? F. K.,of La.—Your plau for disinfecting the U. S. frigate Huquehanna by the fume-* of sulphur w old not be so effective or ao simple as the use of chlorine which we have ttlready proposed. IC. & G-. P., of Mass.—To "case harden." iron,mate up a paste of powdered prussiatt; of potash and water ; coat the iron with this paste, and set it aside to dry. Let the forge fire be clear and bright, and when the paste is dry upon the iron insert the article in the fire until it becomes of a cherry red color. Keep it at this heat for a few minutes, then take it out, plunge it into cold water, and it will be found converted into steel at the surface—case hardened. W. J. V., of N. Y.—The soda water which is sold in drug stores really contains no soda, but it is a solution of carbonic acid gas in water under pressure. To manufacture it requires costly apparatus. The sirups are the juices of fruit boiled with sugar, to keep them from acidifying. A cheap glass of soda water may be made by dissolving in half a tumbler of water a teaspoonf ul of bi-carbonate of soda, and then add a spoonful of powdered white sugar ; in another haH'tumbler of water dissolve a spoonful of citric or tartaric acid, pour into the bi-carbonate of soda, and drink while effervescing. J. K. G., of Pa.—The method that the Chinese adopt in printing water colors from blocks is, to add a small quantity of gum to the color, or else print on very tilightly glazed paper. We do not know the method they use in malcngtheirwater colora. The sample you sent us seems to contain cochineal. F. 51., of N. J.—The beat colors you can uae for painting magic lantern slides are those called by colormen " dny silica colors," and they should be ground with transparent varnish, not oil, and thinned for use with turpentine. McM. & H., of Ohio.—We have no records of a coin-pon magnet having its lifting power increased by inclosing the weight to be lifted in an iron tube ; the principle of action, however, is well-known. Thus in arming magnets their lifting power is increased by gradually adding pieces of iron to the arming weight. J. C. B., of La.—To give all the information you want in regard to the manufacture of candy, artificial beer, cider and wine, in a practical manner, would require more than a whole column of our paper. We cannot give the explanation you want in regard to the rule. K. P. B., of N. J.—The frogs and red worms which are oftentimes seen in great numbers covering the surface of the ground, after a shower in summer, generally come out of the ground ; they do not fall from the clouds. There are instances on record, however, of showers of fish and worms, which must have been carried from a distance by a whirlwind. A shower of small worms fell on the top of the snow in Virginia, during the winter preceding the last. It was supposed that they were carried by a strong wind from a considerable distance south. D. L. P., of Muas.—To render paper partially waterproof prepare it as follows :—Make up a weak solution of aoap containing a very small quantity of glue, and immerse the paper in it until it is wet through. Now take it out, dip it into a solution of alum, and dry it. The article on making water-proof paper to which you refer, is credited to Professor Muschamp. Protoborate of manganese is not for sale in this city. The common oxyd is used for preparing drying oils ; its price is 12 cents per puund. We can furnish Vola. 6, 7 and 12 ; alao back numbers of this Vol. Scr. AM. Money received at the Scientific American Office on account of Patent Office business, for the weekending Saturday, June 26, 1858 :— P. T. B., of 111., $30 ; A. S.% of Pa , $30 ; M. J. B., of Tenn.,$30; II. L. A., of Wis., $35; A. S.,of N. Y., $55 ; D. C. Jr., of Ala., $25 ; J. W., of N. Y., $35 ; C. &N., of 111., $25; F. C, of N. Y.,$10; E. M. S.,ofN. Y.,$30; J. J., of N. Y.. $20; A. F. B., of Wis., $30; J. B., of N. Y., $20; L. E. H., of N. Y., $35; E. H. N., of Conn., $47; P. P. T., of Vt., $25; T. K. R., of Ohio, $30; D. B.. of N. Y., $25; J. N., of Conn., $25; A. T., of N. J., $10; S. R. B-, of N. Y., $25; J. L., of Ind., $30; J. H. R.. of III., $31; P. D. B., of N. J., $30 ; S. K. W., of 111., $25; O. L. C, of 111., $250; F. J. G., of N.C.,$2U; W. K. WM of Mass., $30; O.R.B.,ofN. Y.,$45; It. B.,of N. Y.,$30; W. P., of Mo., $35; E. , C., of N. Y.,$30; G. W. L., of Tex., $27; E.D., of . La., $55; J. J. W., of L. I., $25; T, B. B. ,of Conn., ; $10: D. C. K-, of III., $30; K. L. M., of Ohio, $25; J. P., of Ohio, $30; E. W. K, of HI, $30; G. C, of N. Y., $55; E A.,ofN. Y.,$57. Specifications and drawings belonging to parties with the following initials hsve been forwarded to the Patent Office during the week ending Saturday, June 26,1858 :— I* E. H.. of N. Y. ; E. H. N., of Conn. ; G. W. L., of Texas ; J. H. N., of Iowa ; D. B., of N. Y. ; B. & P. of Maes. ; S. K. W., of III. ; I. L. M., of Ohio; W. P., ot Mo. ; D. O. Jr., of Ala. ; M. J. B., of Tenn. ; M. & B.. of Mich. ; J. J. W., of L, I. ; W. H. Van G., of N. J. ; W. K. W-, of Mass. ; S. K. B., of N. Y. ; O, R, B., of N. Y. ; II. L. A., of Wia. ; C. & N., of III. ; E. A., of N. Y.
This article was originally published with the title "Correspondents"