COLORED DAGUERREOTYPES ON COPPER.--To effect this, take a polished plate of copper and expose it to the vapor of iodine, or bromine, or the two substances combined; or either of them in combination with chlorine. This gives a sensitive coating to the surface of the plate, which may then be submitted to the action of light in the camera. After remaining a sufficient time in the camera, the plate is taken out and exposed to the vapor of sulphuretted hydrogen. This vapor produces various colors on the plate, according to the intensity with which the light has acted on the different parts; consequently a colored photographic picture is obtained. No further process is necessary as exposure to light does not effect the picture. By this process we have an advantage over the silvered plate, both in economy, and in the production of the picture in colors. INSTANTANEOUS PICTURES BY MEANS OF GALVANISM.--It will be seen by the following valuable communication that galvanism can be successfully applied in producing pictures instantly; a process of great importance in securing the likeness of a child, or in taking views of animated nature. Colonel Whitney informs me that he once took a view of the steeple of the St. Louis Court House after sundown by this means, and also secured the image of a man in the act of stepping into a store, and before he had time to place his foot, raised for that purpose, on the door step. Mr. Whitney is well known as the talented editor of the Sunday Morning news. New York, January 16, 1849. Mr. H. H. SNELLING. Dear Sir,--As you are about publishing a history of the Daguerreotype, and request a description of my mode of taking pictures instantaneously by the aid of galvanism, I comply with great pleasure.