On the 21st of last September, a patent was granted to Theodore G. Bucklin, of Troy, N. Y., for a new and improved mode of coating iron with copper, which promises to be an invention of no small importance to the arts. It has long been a desideratum to coat iron with some other and less oxidizable metal, in order to render it more enduring in exposed situations. It is more essential to have sheet and plate- iron than any other kind, covered with copper. For example, sheet-iron covered with copper, would be cheaper than tinned iron for roots of buildings, &c., and plate-iron, if covered with copper, would be excellent for making steam boilers so as to prevent incrustations, &c. Cheapness is an important item in the process. If the process is expensive, then it can be of no general benefit, for pure copper would be preferable. It cheap it is a most important discovery. A method of covering iron with brass, copper, &c., has long been known, but to cover it and make the copper unite with the iron, like tinned iron, has hitherto been considered problematical. The invention of Mr. Bucklin promises to fulfill every condition desired in making coppered iron—cast, malleable, and wrought iron can be coated with copper by the new invention. The process consists in first removing the oxide from the iron to be coated, then covering it with a medium metal which has a great affinity for the iron, and afterwards dipping the iron so prepared into molten copper, which, by the galvanic action of the medium metal, makes the copper intimately combine with the iron, and form a complete coating. The oxide is removed from iron by means of diluted sulphuric acid, in which the castings or sheets are rubbed with sand; after this they are washed, and dipped into a solution of the muriate of ammonia dissolved in a suitable vessel, when they are ready for the next process. This consists in dipping the sheets or plates into molten zinc, immediately after they are litted out of the salammoniac solution. The surface of the molten zinc should be covered with dry salammoniac, to prevent the evaporization of the metal. The iron is soon covered with a coating of zinc, and forms what is termed galvanized iron. At hand, the operator has a crucible or pot containing melted copper covered with some incombustible substance as a wiper, and he at once dips the zinced iron, into this, in which it is kept until it ceases to siss, when it is taken out and found to be covered with a complete and durable coating of copper, By dipping the iron thus coppered, into the solution of salammoniac, ' then into the zinc, and the copper—repeating the process—coat upon coat of the copper will be obtained, until it acquires any degree of thickness. The black oxide is prevented from forming on the copper by dipping it afterwards in the salammoniac solution, and then washing it in pure water. This process is entirely different from that of Mr. Pomeroy, for which a patent was granted a few years ago, and which was published on page 69, Vol. 6, Scientific American. We have seen samples ofiron coated by Mr. Buck lin's process, which were very beautiful and well covered. Unless the melted copper was covered with a non-combustible substance, the plates would come out in a very rough state but the covering acts as a wiper, and the coppered plates come out smooth, and well coated. Brass, or any of the copper alloys, can be made to coat the iron, in the same manner as the copper. We hope this new process will be the means of extending the use ot sheet-iron, soi as to save considerable to the country, that is now paid out for tinned sheets.