COLLO'DIONIZED PAPER PROCESS. Paper being substituted for glass in this pro cess, as a basis upon which to support the film, a great increase in portability is arrived at, as the sensitive sheets may be carried in a portfolio, and employed in the same man• ner as dry collodion plates. There are difficulties, however, in the way of its successful practice, which have prevented it from becoming as popular as it deserves to be. The following is a brief summary of the manipulations. Mr. Corbin, the inventor of the process, ascertained that a peculiar collodion was requisite, the formula of which is as follows: ether, 650 parts; alcohol, 350 parts; pyroxylin, 15 parts; iodine, 1• parts. The collodion so prepared is poured on the glass in the usual way, and sensitized in a bath containing only 1 per cent of nitrate silver, and a per cent of nitric acid. The plate having remained in this bath about 2 minutes, is withdrawn, and freely washed with water; it is then immersed in a solution of 1 per cent of iodide of potassium, to insure the complete decomposition of the whole of the free nitrate of silver not removed by the washing. A piece of negative paper is now coated with a solution of gelatine,
containing 6 parts of gelatine to 100 parts water; the dimensions of the paper should be rather less than the glass, and the gelatinized side is brought into contact with the collo dion film in a dish of water, any intervening water being expelled by passing a glass rod lightly over it. The edges of the collodion film which project beyond the paper are folded back oh it, and the film and paper removed together. The now collodionized paper is laid, film uppermost, on a glass plate, coated with a preservative solution, com posed of equal parts of albumen and honey, diluted sufficiently to enable it to flow freely over the paper. The film is lastly sensitized in a solution of nitrate of silver, 5 parts; glacial acetic acid, 5 parts; water, 100 parts; it is then freely washed as before in water, and hung up to dry. As it is apt to wrinkle in drying, it should be attached by all four corners to two lines, running one under the other.