Such is the hand-method, very largely adopted. This manufacture, however, has (shared iu many of the advantages which mechanical ingenuity hag conferred upon letter-press printing, by the adoption of the cylinder. About the year 1840, Messrs. Potter, of Darwen, intro duced machine-printing into the trade. By means of steam-power, artificial drying, and an endless roll of paper, they were enabled to produce patterns with good effect for paper-hangings, by surface-roller printing in different colours. Year by year has this art, improved, until at length some of the patterns are produced by as many as four teen cylinders, each printing one particular colour. This number of colours has even been increased to twenty, by a peculiar management of the cylinders. The machines can now print 20,000 yards in a day each, if simple in device and colours. The immense extension of the paper-hanging manufacture within the last few years, and the lowering of price, are mainly owing to this use of steanspower cylinderprinting. AU the best work, however, is still done by hand (as in book-printing and calico-printing).
Besides the inure usual varieties of paper.hangings, there are many special kinds. Sonic have a glossy or satin ground. To produce this, a ground of satin white, properly tinted, is laid on ; this ground is then rubbed with powdered French chalk worked by means of a brush, until a gloss is produced. After this the printing proceeds as usual.
These satin papers sometimes receive an additional beauty, by being passed between two slightly heated rollers, one of which has an engraved pattern in imitation of watered and figured silk, &c. : this pattern is thus imparted to the paper. Flock papers are those in which a portion of the pattern somewhat resembles woollen cloth. We have already spoken of these, as originally produced ; but in the present mode of manufacture, when the proper ground-colour has been applied, the device is printed, not with a coloured pigment, but with japan gold-size ; and on this gold-size is sprinkled the flock, consisting of fragments of woollen cloth eut into a sort of down and dyed. The flock adheres to the gold size and can easily be brushed off the other parts. Sometimes flocks of two or three colours are employed ; these are laid on at separate times. The French have acquired much skill in the preparation of these flock papers : some of their embossed and shaded flocks are very beautiful. Striped papers are sometimes pro duced in a singular manner. The colour (rather more liquid than in other cases) is contained in a trough having parallel slits in the bottom. The paper is made to pass quickly under the bottom of the trough, by means of a revolving cylinder, and thus obtains a deposit of colour in parallel lines, through the slits in the bottom of the trough. By a modification of this method is produced what is termed a b!ended ground. A trough, containing many distinct cells, is filled with
various tints of any given colour, one tint to each cell. A long narrow brush being dipped into all these cells, takes up a portion of each tint, which it applies to a roller ; from the roller the pigment is transferred to a revolving brush, and from the brush to the paper. Thus is produced a blended or shaded ground, which afterwards receives any desired pattern. Bronze or imitation gold-powder is frequently applied to papers. A device being printed in japan gold-size, the powder is lightly rubbed over the paper, and adheres to the gold-size. The remainder of the pattern is commonly printed in colours. In some wall-papers, leatgold, silver, or copper is applied to a portion of the pattern : this is a slow and expensive process. Other kinds, again, in order to bear washing or cleaning, are printed with colours mixed with oil or varuish lnstead of aize. A modern kind called oak paper is pro duced in a remarkable way ; the grain is printed from a piece of real oak, and is thus more true to nature than any block engraved by hand ; by shaving off a few fibres, a new pattern of grain can be developed at pleasure. Among various novelties in the manufacture, one relates to the printing of the pattern in a direction transrer,e to the direction of the paper, and pasting the paper horizontally on the wall ; the inten tion seems to be, to diversify the effect, by removing a sameness resulting from the usual plan.
A matter of a remarkable and somewhat important nature has lately come under public notice, in connection with the use of arsenic in the colouring of paper-hangings. Certain tints of green are produced, more permanent than other kinds available to pap er-stainere ; and these permanent greens contain arsenic. When a committee of the House of Lords was collecting evidence on the " Sale of Poisons " bill, in 1857, Dr. A. S. Taylor brought forward this subject. Ile stated that arsenic is more largely used for these greens than in any other English manufacture ; and that workmen, an well as the occu pants of houses, suffered thereby. Constriction of the throat, nausea, head ache, loss of appetite, fic. result. Instances had come under his notice, as a physician, tending to prove that rooms, hung with paper coloured with arsenic greens, are very prejudicial to health. Another physician, Dr. Hinds, detected a minute trace of arsenic in loaves of bread which had been placed on the shelves of a newly-papered ehop, the paper being brilliant with arsenic-green. A working paper-hanger inf. rued Dr. Taylor that he always suffered from inflamed eyes and nose, sickness, and giddiness, on the days when he was engaged upon green papers. The Prussian government, attending to the cautious of physicians and chemists, forbid the use of arsenic in any colours, whether distemper, or oil, for indoor work.