Jameson, 1870. Printed on paper, designs with ferrocyanide of potassium and then soaked the paper when dry in a solution of oxalic acid in alcohol. Duthie, 1872. Made a ground work of writing ink of different colors by any known means of pen ruling. Syms, 1876. Produced graduated colored stains, which were made to partially penetrate and spread in the pulp web. Van Nuys, 1878. Colored the Paper with a pigment and then printed designs with a soluble sulphide. Casilear, 1878. United two distinctive colored papers, one a fugitive and the other a permanent color. Hendrichs, 1879. Dipped ordinary paper in an aqueous solution of sulphate of copper and carbonate of ammonia and then added alkaline solutions of cochineal or equivalent coloring matter. Nowlan, 1884. Backed the ordinary chemical paper with a thin sheet of waterproof paper. Menzies, 1884. Introduced iodide and iodate of potassium or their equivalents into paper. Clapp, 1884. Saturated paper with gallo-tanic acid, but the ink used on this paper contained ferri-sesquichloride or other similar preparation of iron. Hill, 1885. Introduced into paper, ferrocyanide of manganese and hydrated peroxide of iron. Schreiber, 1885. Colored paper material with indigo and with a subsequent treatment of chromates soluble only in alcohol. Schreiber, 1885. Treated finished paper with ferric- oxide salts and with ferrocyanides insoluble in water but soluble in acids. Schlumberger, 1890. Impregnated white paper with a resinated ferrous salt, a resin compound of plumbic ferrocyanide, and a resin compound of ferrocyanide of manganese in combination with a salt of molybdenum and a resin compound of zinc sulphide. Schlumberger, 1893. Dyed first the splash fibers and mixed them with the paper pulp. Second. He also treated portions of the surface with an alkali, so as to form lines or characters thereon, then immersed the same in a weak acid, in order to produce water-mark lines. Carvalho, 1894. 1. Charged the paper with bismuth iodide and sodium iodide. 2. Charged the paper with a bismuth salt and iodide of soda in combination with primulin, congo red or other pigment. 3. Charged the paper with a benzidine dye and an alkaline iodide. 1895. Applied a compound, sensitive to ink erasing chemicals, AFTER the writing has been placed on the paper. Hoskins and Weis, 1895, a safety paper having added thereto a soluble ferrocyanide and a per-salt of iron insoluble in water but decomposable by a weak acid in the presence of a soluble ferrocyanide, as and for the purpose described. (2) A safety paper having added thereto a ferrocyanide soluble in water, a per-salt of iron insoluble in water but easily decomposed by weak acids in the presence of a ferrocyanide soluble in water, and a salt of manganese easily decomposed by alkalis or bleaching agents, substantially as described.