To determine whether the saline residue contained a bromide, a small portion of it was treated in a tube with pure nitric acid, and a yellow liquid was immediately obtained. Another portion was mixed with peroxide of manganese, and the mixture was placed in a glass tube; a few drops of concentrated sulphuric acid were added, and when gently heated, red vapors were immediately disengaged, and alter some lime there were deposited on the sides of the tube small drops of a red liquid. The existence of bromine was therefore evident, and it was proved that the bromide was unmixed with iodide. Bromide of silver appears to be rare at Huelgoeth; but it may be readily distinguished from the chloride by its greenish or canary-yellow color, which is characteristic of it. It is remarkable that it occurs with the chloride in the same specimens, but without there being an intimate mixture of the two substances.
Since the announcement of the Hillotype, in the last number of the Daguerreian Journal, quite an excitement has prevailed, both in the Daguerreotype and scientific world. The great question has fairly been solved and "_natural colors_" can be produced and rendered indelible upon the metallic plate. America can safely say she has presented to the world one of the most invaluable discoveries that has ever been imprinted upon the pages of history.
Men profound in their scientific skill and learning, have long and in vain sought for the discovery or invention of some means of securing to the future, the colors of the present. All Europe has been alive to this great desideratum, and many have presumed it an impossibility, while some few persisted, flattered by hope and encouraged by the almost daily announcement of some new discovery or invention, that heretofore had been deemed only as having existence in the dreamy imagination or a perspective future. We hail the discovery of the Hillotype as an epoch bright in the history of science, as well as impregnated with interest to aid in unfolding a volume of investigation which has so long commanded the attention of learned and philosophical minds, as the "_colored rays of light_."
The subject of reflected light and its colors has long agitated the scientific mind. Much has been said and written; elaborate and laborious "Essays," "Researches" and "Treatises" have penetrated our libraries and proved valuable auxiliaries in pushing the interest of those engaged in furthering agricultural and chemical pursuits. This branch of natural science is regarded as one of the most important, and, at the present moment, it is rendered doubly interesting from the fact of Mr. Hill's discovery. We may look forward for new developments, which will prove no less surprising than that of rendering permanent, on a metallic plate, the variegated beauties of the solar spectrum.