Use, &c. Lithographic paper is written on with lithographic ink. The writing is transferred by simply moistening the back of the paper, placing it evenly on the stone, and then
applying pressure a reversed copy is obtained, which, when printed from, yields corrected copies resembling the original writing or drawing. In this way the necessity of executing the writing or drawing in a reversed direction is obviated. See Lithography, Ink, &c.
Paper, Paste. Boil white paper in water for five hours; then pour off the water, and pound the pulp in a mortar; pass it through a sieve and mix with some gum water or isinglass glue. It is used in modelling by artists and architects.
Paper, Oiled. Prep. Brush sheets of paper over with ‘boiled oil,’ and suspend them on a line till dry. Waterproof. Extensively employed as a cheap substitute for bladder and gut skin to tie over pots and jars, and to wrap up paste blacking, ground white lead, &c.
Paper Parch′ment. Syn. Papyrin, Vegetable parchment. Prep. 1. (Poumarède and Figuier.) Dip white unsized paper for half a minute in strong sulphuric acid, sp. gr. 1·842, and afterwards in water containing a little ammonia.
2. (W. E. Gaine, Patent 1857.) Plunge unsized paper for a few seconds into sulphuric acid diluted with half to a quarter its bulk of water (this solution being of the same temperature as the air), and afterwards wash with weak ammonia. This process, now extensively worked by Messrs De la Rue and Co., produces a much better material than does that of Poumarède and Figuier.
Prop. A tough substance, resembling animal parchment, and applicable to the same purposes. It is largely used for covering pots of pickles and preserves, and by the chemist for the intervening membrane in experiments in diffusion. See Dialyser, Dialysis, &c.
Paper, Protective. Various attempts have from time to time been made to prepare paper which might make the fraudulent alteration of cheques and other documents difficult or impossible. These attempts have taken two different directions, which may be briefly described.
The first and best known method consists in printing, in some delicate and easily destroyed colour, a complicated pattern on the face of the paper. Any reagent which will remove the writing will, of course, destroy the pattern below, and so render the alteration evident. The cheques used by Messrs Coutts and Co. are fine examples of this kind of protection, the whole of the paper being printed over with the name of the firm in characters so delicate, that they can scarcely be read without the assistance of a lens.
The obvious objection to this method is, that it is possible for a skilful forger to replace the printed design before the completion of the alteration.