268 USEFUL FIBER PLANTS OF THE WORLD. 



favor as a very pure and easily obtainable form of cellulose. Two main processes 

 for its production are now in use, the caustic soda process and the bisulphite 

 process. In the former, the wood chopped up and crushed is boiled under pressure 

 with caustic soda. This is either done in cylindrical boilers at pressures varying 



from 4 atmospheres (60 pounds;, as first used by Watt and Burgess, To 1 1 atmospheres 

 (210 pounds . as used by Sinclair, or by lingerer's graduated method ina series of 

 nine connected vessels, using low pressure and partly saturated lyes upon the fresb 

 wood and increasing the pressure and using fresher lyes upon the partly converted 

 wood. Somewhat more than 50 per cent of the soda used is recovered again from 

 the washings. The alkali process is, however, being gradually displaced by the 

 bisulphite process. As first proposed by Mitscherlich, acid calcium sulphite was 

 used. The temperature is brought gradually to 118 c C. which is not exceeded, the 

 pressure being from 2 to 3 atmospheres. In Ekman's process, acid magnesium sulphite 

 is used, and a pressure of from 5J to 6 atmospheres is attained. Still another process 

 is that of Franke, which uses bisulphite of lime again. Cross and Bevan explain 

 the efficacy of the bisulphite processes by saying: 



"The chief agency is the hydrolytic action of sulphurous acid, aided by the con- 

 ditions of high temperature and pressure; and the subsidiary agencies are : (1) The 

 prevention of oxidation: (2) the removal from the sphere of action of the soluble 

 products of resolution in combination with the sulphite as a double compound, for 

 it is to the class of aldehytes that we have shown that the noncellulosic constituents 

 of wood belong, and (3) the removal of a portion of the constituents in combination 

 with the base. i. e.. with expulsion of sulphurous acid." 



The several bisulphite processes, as compared with the ones mentioned previously, 

 yield a larger amount of pure fiber. They preserve its original strength, which is 

 not done when caustic soda acts upon the loosened fiber under pressure, and there is 

 a greater economy of chemicals. 



In Dr. Fernow's account of the wood-pulp industry the following classes are rec- 

 ognized: (1) The mechanical or ground pulp is produced by grinding the wood after 

 proper preparation on rapidly rotating stones under constant rlow of water (Yoelter 

 process). (2) Brown wood pulp, mainly a mechanical pulp, except that the wood is 

 steamed before grinding, under a pressure of 2 to 6 atmospheres. (3 ) Chemical wood 

 pulp, or cellulose proper f in this country called " chemical fiber "'). is produced by treat- 

 ing finely divided wood or wood shavings with various chemicals, which dissolve or 

 render soluble the incrusting substances, leaving the fiber as long, elastic, and pure 

 as the raw material will furnish it. while the above mechanical processes naturally 

 shorten and deteriorate the fiber mechanically. The chemical processes can be again 

 classified into alkaline and acid processes, according to the kind of chemicals used. 



By the alkaline processes are obtained soda pulp and sulphate pulp. The acid proc- 

 esses are more numerous. Electro pulp is derived from a more recent process, in 

 which the wood is digested in a solution of common salt, at 250° to 260 : constantly 

 electrolyzed. For detailed accounts of these processes, see Report of the Division 

 of Forestry. Annual Report of the United States Department of Agriculture for 189 ': 

 Cellulose, by Cross and Bevan: and Sadtler's Handbook of Industrial and Organic 

 Chemistry. The wood-pulp industry in 1890 represented 183 mills, located in 22 

 States, and with a total daily capacity as follows: Mechanical or ground pulp. 

 407,000 pounds: chemical soda fiber, 149,000 pounds: chemical sulphite fib r. ll a 

 pounds. The average yield per cord is 1,700 pounds for ground pulp, 1,000 for sul- 

 phite, and 800 for soda pulp. By the different processes the value of a cord of wood 

 may be brought to $24.50 to $30. 



"In 1888 the stumpage consumed for pulp was valued at $2,235,000. The product. 

 225,000tons ground and L12,500tons chemical pulp, was valued together at $12,375,000, 

 the capital employed being estimated at $20,000,000. The consumption, in round 

 numbers, wae indicated in 1890 to amount to 1,000,000 cords of wood per annum. 

 When it is considered that about 1,000,000,000 pounds of book and news paper are 



