A good varnish may be drawn into threads like glue, and is very thick and tenacious. The oil loses from 10% to 14% by the boiling. Mr Savage obtained the large medal of the Society of Arts for his black ink made as above.
A printer’s ink easily removed from waste paper. The following process for the preparation of a printer’s ink that can be far more readily removed from waste paper than ordinary printer’s ink has been patented by Kirscher and Ebner. Iron is dissolved in some
acid—sulphuric, hydrochloric, acetic, &c., will answer, and half of the solution is oxidised with nitric acid and added to the other half and the oxide precipitated from the mixture by means of soda or potash. The precipitate is thoroughly washed, and treated with equal parts of solutions of tannic and gallic acids, and the bluish black, or pure black pigment formed, is thoroughly washed and dried, and mixed with linseed-oil varnish, and can then be immediately used for printing from type, copper, wood, steel, or stone. Waste paper printed with it can be bleached by digesting it for 24 hours in a lukewarm bath of pure water, and 10 per cent. of caustic potash or soda, and then grinding it well in the rag engine, and throwing the pulp upon cloth and allowing it to drain. It is then to be washed with pure water, containing 10 per cent. of hydrochloric, acetic, or oxalic acids, or of binoxalate of potassa, and allowed to digest for 24 hours, and may then be worked up into paper, or it can be dried and used as a substitute in the manufacture of finer paper.
PRINTS (Ackerman’s Liquor for). Prep. Take of the finest pale glue and white curd soap, of each 4 oz.; boiling water, 3 pints; dissolve, then add of powdered alum, 2 oz. Used to size prints and pictures before colouring them.
PRINTS, To Bleach. Simple immersion of the prints in a solution of hypochlorous acid (the article remaining in the solution for a longer or shorter space, according to the strength of the solution) is generally all that is required to whiten it.
PRIVIES. See Water-closets.
PROOF. See Acetimetry, Alcoholometry, &c.
PROOFS (Correcting). The specimen below, with the notes, will, if carefully perused, put the reader into possession of all the secrets of this useful art.
[The same corrected.]