It will be remembered that an island, about 120 feet high and 2,000 feet in circumference, suddenly sprang up in 1831 between Sicily and La Pantellaria. It disappeared about a month after, and at a later period even the sounding lead could give no indications of its existence; but vessels passing over the place it had formerly occupied would sometimes feel a sort of shock, which showed that it was of volcanic origin. In March last, however, the French vessel Eole, which was taking soundings in the vicinity, discovered some traces of its existence; and we now learn from Naples that in the course of the last month Her Majesty's ship Scourge, Captain Kerr, verified the truth of the preceding observation, and further discovered that the island, which had been christened "Isola Giulia," was only nine feet under water. Captain Kerr had a pole with a streamer and an inscription set up on the spot. * * * * * The experiments for the production of PHOTOGRAPHS in NATURAL COLORS appears to have been carried on simultaneously by Mr. Hill in this country and by several persons abroad. The _Athenæum_ says that in some experiments made by Sir John Herschel a colored impression of the prismatic spectrum was obtained on paper stained with a vegetable juice. Mr. Robert Hunt published some accounts of the indications of color in their natural order obtained on sensitive photographic surfaces. These were, however, exceedingly faint, and M. Biot and others regarded the prospect of producing photographs in colors visionary,--not likely, from the dissimilar action of the solar rays, ever to become a reality. M. Becquerel has a process by which, on plates of metal, many of the more intense colors have been produced; but it appears to have been reserved for the nephew of the earliest student in photography, Niepce, to produce on the same plate, by _one_ impression of the solar rays, all the colors of the chromatic scale. Of this process, called by the discoverer, _Heliochromy_--sun-coloring--we have had the opportunity of seeing specimens. They are three copies of colored engravings,--a female dancer and two male figures in fancy costumes; and every color of the original pictures is faithfully impressed on the prepared silver tablet. The preparation of the plates remains a secret with the inventor, but the plate when prepared presents a dark brown, nearly a black surface, and the image is _eaten out_ in colors. We have endeavored by close examination to ascertain something of the laws producing this remarkable effect; but it is not easy at present to perceive the relations between the colorific action of light and the associated chemical influence. The female figure has a red silk dress, with purple trimming and white lace. The flesh tints, the red, the purple, and the white are well preserved in the copy. One of the male figures s remarkable for the delicacy of its delineation:--here, blue, red, white and pink are perfectly impressed.