Page:Popular Science Monthly Volume 42.djvu/222

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themselves more readily to the fanciful forms which manufacturers like to impose upon them.

M. A. Petit, engineer, has described to us the processes of manufacturing them thus: A paper pulp is taken composed of eighty-five parts of wood pulp and fifteen parts of rag pulp, and is shaped in molds to the desired form. The pneumatic or the centrifugal process of molding is used, according to circumstances, and does not differ essentially from those employed in porcelain factories. The articles are dried in air and then desiccated in a current of warm air; after which they are placed in an iron cylinder of one cubic metre capacity, which can be hermetically closed. A vacuum is formed in the cylinder in order to withdraw the air from the objects which are placed in it, and is maintained for four hours, after which a liquid composed of petroleum essence, colophony, linseed oil, and paraffin is admitted; this liquid being heated to a temperature of 75° C. before it is let into the cylinder. The articles are kept immersed in it for a quarter of an hour, when they are withdrawn and placed in a similar cylinder heated to 100° C, for the purpose of expelling the petroleum and recovering the solvent for use in other operations. The articles having been dried, are exposed in a stove for five hours, at 75° C, in a current of electrified air, or air containing a considerable quantity of ozone, for the oxidation of the linseed oil which fills the pores of the pulp. They are then plunged for an hour in a bath of linseed oil, castor oil, and colophony; exposed again in the stove to air and ozone, after which they are completely impermeable, flexible, and proof against acid.

The adaptability of paper for the construction of canoes has been proved by the strictest tests, and the canoes have been found to be practicable boats; but the manufacture of them has not been as prosperous an industry as might have been anticipated.

On the other hand, the application of paper in house-building has been crowned with success. A builder's establishment founded several years ago took for its device "Neither wood nor iron"; and its houses, built almost exclusively of pressed paper, are curious specimens of what may be done with that material. The element of the construction is a panel, usually three metres by one metre and sixty centimetres, and a tubular beam ten centimetres in thickness, and composed of two walls of pressed paper four millimetres in thickness, fixed upon a frame, likewise of paper. The pieces composing this frame are V or U shaped; and these devices, capable of giving extremely light joists or beams, are not one of the least original of the conceptions of the system. The elementary panels do not weigh more than forty kilogrammes apiece; they are easily handled, and they fit at their edges so as to constitute the wall. The roof is com-