surface for writing, the Egyptians provided themselves with excellent paper.
European papermaking dates from the eleventh century, and English papermaking from the fifteenth century. The colophon to Wynkyn de Worde's "De Proprietatibus Rerum" mentions the paper mill of John Tate at Stevenage in Bedfordshire. Early English papers were made from rag fibres, and rag papers still hold the premier place.
Cellulose is the substance of which the permanent cell membranes of plants are composed, and it forms the bulk of the tissues of wood and similar plant structures. In most cases the presence of colouring matter and various waxy and resinous substances taken up by the growing plant render the cellulose very impure, and it is desirable that, as far as possible, all impurities should be removed before the fibres are made into paper. Cotton is the purest form of cellulose found in nature, 91 per cent. of the natural cotton fibre being pure cellulose, while esparto yields only about 50 per cent. of its weight as cellulose. Notwithstanding the many different varieties of plants, the chemical composition of the fibres is practically identical. One of the principal characteristics of cellulose is its extreme permanence, which is principally due to the fact that it forms but few chemical combinations with other substances.
Vegetable fibres of all kinds may be converted into paper, but no new fibre threatens those now employed, unless it can be obtained in large quantities, responds readily to the usual bleaching reagents, and can be delivered to the papermaker at a price which enables it to compete successfully with the fibres at present in use at the paper mill. In some cases the plant fibres are reduced to pulp near the place of growth, in others the raw material is transported in its entirety. Other
