(1) A really incombustible paper, without a fireproof ink, would be a very valuable article in many businesses, and for many purposes of every-day life, but if it can be supplemented by a fireproof ink, its value will be enhanced tenfold. Such a discovery G. W. Halfpenny believes he has made, and that paper prepared by his process, under such circumstances as fires in houses, factories, or other buildings, is "ordinarily incombustible.*' The inventor prepares his paper in the usual manner from a pulp consisting of vegetable fibre, asbestos, alum, and borax, in or about the following proportions: - Vegetable fibre, 1 lb.; asbestos, 2 lb.; borax, 1/10 lb.; and alum, 1/5 lb. The vegetable fibres are minutely divided, and treated in the manner usual in the production of ordinary paper; the asbestos is also divided as much as possible, and the two are then intimately mixed with the alum and borax in a sufficient quantity of water to make a pulp of the requisite consistency, which is then made into paper by any of the well-known processes. The proportions given may be varied to suit the quality and nature of the desired product, and also to suit the different qualities of the raw materials.
Thus the inventor says he has made incombustible paper in which the proportions of the ingredients varied from 50 to 70 parts of asbestos, and from 30 to 50 parts of flax or other vegetable fibre, with only 2 1/2 per cent, each of alum and borax. He proposes to use in some cases silicate of soda, in order to ensure hardness and coherence in the substance of the paper after it has been acted upon by fire. In order to obtain a paper of great strength and flexibility, the sheets may be made of linen or other woven fabric, and coated on both sides with the incombustible paper. The fireproof ink for use in writing or printing on the incombustible paper is made of the following substances: - Graphite, 22 dr.; copal or other resinous gum, 12 gr.; sulphate of iron, 2 dr.; tincture of nutgalls, 2 dr.; and sulphate of indigo, 8 dr. These materials are mixed together and boiled in water, the graphite of course being reduced to an impalpable powder. This ink, which besides being fireproof is said to be insoluble in water, under ordinary circumstances is black; but when coloured inks are desired, the graphite is replaced by an earthy or mineral pigment of the desired colour.
(2) Fire-proof paper was prepared by L. Fro been by bleaching choice asbestos fibres with sulphurous acid, and adding 5 per cent, of ground wood-fibre with borax or glue-water, and worked into paper; it can be nicely smoothed, and is said to resist a white glow heat.
(3) The 'Chemiker Zeitung' gives the following modes of preparing incombustible writing and printing paper, which appear worth attention: - The best asbestos is treated with a preparation of permanganate of potash and then with sulphuric acid; 95 per cent, of this asbestos is mixed with 5 per cent, of wood-pulp in water containing borax and glue. A fireproof writing-ink is made by mixing Indian ink and gum with chloride of platinum and oil of lavender; for printing-ink lampblack and varnish are to be substituted.
(4) Paper made of pure asbestos resists a high temperature without material alteration. An ammoniacal solution of nitrate of silver, coloured with a little Indian ink, will preserve a legible copy when written with on the asbestos paper mentioned above, and subjected to strong heat.
(5) A free-flowing ink for writing on fireproof paper with an ordinary metallic pen may be obtained by using 5 parts dry chloride of platinum with 15 of oil of lavender, 15 of Chinese ink, and 1 of gum-arabic, adding thereto 64 of water. When the paper is ignited after being written upon with this ink, the platinum ingredient causes the writing to appear transparent, and, as a consequence, it is claimed that such writing as has become black or illegible will become readily legible again during the process of heating the paper. Colours for painting may also be made fireproof by mixing commercial metallic colours with the chloride of platinum and painters' varnish, adding an ordinary aquarelle pigment to strengthen the "covering power " of the colour. These fireproof paints or colours can be easily used in the same manner as the common water-colours, and it is claimed they will resist the destructive influence of great heat quite as successfully as the fireproof printing and writing inks just referred to.
Much useful information will be found in W. G. McMillan's paper on " Some Causes of Fire and Methods for their Prevention" (J/. Soc. Arts, vol. xxxi, No. 1581, pp. 380-96).