The tensile test — one c£ many tests used in 

 evaluating paper quality. 



the factors of time, temperature, and 

 concentration of chemicals in cooking. 

 Research in wood grinding is likewise 

 establishing useful principles of control 

 which are having a wide effect in im- 

 proved quality of pulp and lower power 

 consumption; an extended program o j^ 

 grinding studies is in progress with newB 

 and complete equipment. 



A special contribution of the Labora- 

 tory to the procurement of high yields 

 from the standard and less-used pulping 

 species is the development of the so- 

 called semichemical processes. Where- 

 as the usual chemical methods return 

 only 40 to 50 percent of the wood as 

 useful fiber, the new processes return 

 from 55 to 80 percent. In one of them 

 neutral chemicals are used, in another 

 acid sulphite liquors, and in a third al- 

 kaline reagents. In each process the 

 pulping of the partially cooked wood is 

 completed in a rod mill or other disin- 

 tegrating device. An interesting appli- 

 cation is the conversion of extracted 

 chestnut chips into container board, 

 now proceeding commercially on a large 

 scale. 



The use of a soda or ammonia base 

 for sulphite pulping offers a distinct 

 advantage over the use of the customary 

 lime base, in that the liquors can be 

 effectively applied in cooking not only 

 the common pulpwood species but also 

 the more resinous woods not now reduci- 

 ble by the sulphite process. The Labor- 

 atory is advancing the technique of the 

 new method, by means of which much 

 additional raw material for white papers 

 may be made available to both north- 

 ern and southern mills. Furthermore £ 



M-26399-F 



An experimental Fourdrinier machine, with 

 press and drier rolls and calender, trans- 

 forms the pulp into finished paper. Oper- 

 ating elements are under precise control. 



