Parchment (Fr. parchemin, Lat. pergamena, through Gr. from Pergamus). At a very early period the skins of animals were used for writing upon. Some authors who have written on the subject of ancient writing materials think that the king of Pergamos brought the art of making parchment to perfection through Ptolemy Epiphanes having prohibited the exportation of papyrus from Egypt. The Romans appear to have written chiefly on papyrus, and this practice was continued in Italy till about the 10th century, but parchment was also used; and from that time till ordinary paper became available in the 14th century parchment was almost the only material employed (see PALEOGRAPHY, PAPER). To a limited extent wax tablets and leaden plates were written upon as late as the 14th and 15th centuries, and some of these are preserved at Florence. Some of the earliest printed books were done on vellum (a name originally given to a parchment made of calf-skin), and on a specially fine quality of this substance, made from the skins of calves prematurely born, some of the best of the early miniature portraits were painted. Ordinary parchment is chiefly made of sheep-skins, but those of calves and goats are also used. Fine parchment and vellum are prepared from the skins of kids, lambs, and young calves. A coarser parchment for drumheads, tambourines, &c. is manufactured from the skins of male goats, wolves, and calves. A peculiar kind is made from asses' skin, and for bookbinders' use a parchment is sometimes prepared from pig-skin. The early stages in the manufacture of parchment are the same as for Leather (q.v.). After being unhaird and cleaned, the skins are stretched evenly upon a stout wooden frame called a horse. The flesh side of the skin is first gone over with a double-edged semicircular knife (fleshing-tool) to remove adhering particles of flesh. With the fleshing-tool inverted, to prevent any cutting of the epidermis, the other side of the skin is then scraped to remove dirt and to squeeze out some of the absorbed water. For some purposes for which stout parchment is required the skin is now merely allowed to dry on the frame, no further treatment being required. But fine parchment for writing or drawing upon, some of which is made from split skins, is sprinkled over with sifted chalk on the flesh side and rubbed smooth with a flat surface of pumice-stone. The grain side of the skin also is rubbed over with pumice, but no chalk is used. In these operations great care requires to be taken not to fray the surface, and certain precautions are necessary during the drying of the parchment. Any considerable roughness or unequal thickness is removed by the skin being again scraped and pumiced.
VEGETABLE PARCHMENT.—This substance, which excited much interest and curiosity when it was first introduced, was patented by Mr W. E. Gaine in 1853 (no. of specification, 2834). It is made by dipping ordinary unsized paper for a few seconds in concentrated sulphuric acid mixed with one-half its volume of water, and then quickly removing all trace of the acid. The mixture is allowed to cool before being used. This simple treatment produces a remarkable change in the paper. It acquires a parchment-like texture; turns translucent, especially when thin; and becomes about five times stronger than ordinary paper. Vegetable parchment is also impervious to water, but is rendered soft and limp when dipped into it. The acid produces a molecular change in the Cellulose (q.v.) of which paper consists. A solution of chloride of zinc acts on paper in a similar way. In the manufacture of vegetable parchment a roll of paper is by a mechanical arrangement pulled through a vat containing the sulphuric acid (the time of immersion being from five to ten seconds for thin paper), next through water, then through a weak solution of ammonia, and once more through water. It is afterwards passed through felt-covered rollers, and then calendered. Stout qualities of vegetable parchment have been used for book-covers and for writing deeds upon. Thin sheets of it serve as a convenient material for tracing designs, plans, &c. But it is now chiefly employed for covering jars of preserves and for like purposes.