_Wood-Pulp._--When a purchaser of one of the New York dailies reads the morning’s voluminous edition, he little realizes that he holds in his hands the remains of a billet of wood as large as a good-sized club, yet such is the case. Originally made from the fibres of the papyrus plant, and later from rags beaten into a pulp, paper for the printing of books and newspapers is now made almost entirely of wood. In the formation of paper pulp from wood two processes are employed, one known as the soda process, and the other the sulphite process. In both cases the wood is cut into fine chips, and then digested in great drums with chemicals to extract the resinous matter and leave the pure fibrous cellulose, which resembles raw cotton in texture. This industry was developed by Watt and Burgess in 1853 (U. S. Pat. No. 11,343, July 18, 1854), who invented the soda process; by Voelter (U. S. Pat. No. 21,161, Aug. 10, 1858), who devised means for comminuting or shredding the wood; and by Tilghman (U. S. Pat. No. 70,485, Nov. 5, 1867), who invented the sulphite process. The logs, usually of spruce or poplar, are first split, as seen at the bottom of Fig. 127, then placed in the chipper, where a revolving disc with knives cuts them into small chips, which are fed to an elevator and raised to a screening device, seen at the top, to remove saw-dust, dirt and knots. In the sulphite process the chips are then delivered into the digesters shown in Fig. 128, which are supplied with sulphurous acid generated in a plant shown in Fig. 129. In the digesters the gummy and resinous matters are dissolved by the heat and chemicals, and the woolly fibre left behind is bleached, washed, and dried, and afterwards made into paper upon the Fourdrinier machine. [Illustration: FIG. 127.--CHIPPING LOGS FOR PAPER PULP.] [Illustration: FIG. 128.--DIGESTER FOR WOOD PULP.] [Illustration: FIG. 129.--SULPHUROUS ACID PLANT FOR MAKING WOOD PULP.]