portions of water to remove the last traces of 

 sodium resinate. This final washing yielded small 

 amounts of rosin soap. The chips were then dried 

 in the oven and extracted with ether to determine 

 the percentage of unsaponified rosin left in the 

 wood. This indicated the efficiency of the alkali 

 extraction. 



The sample of chips was finally dried at 105C. 

 and weighed, giving the percentage of dry, rosin- 

 free wood. The difference between the true wood 

 content of the original resinous material and the 

 weight of the wood after alkali extraction showed 

 the extent of solution of the lignocellulose. 



The second stage of the treatment was the pro- 

 duction of pulp from the wood. The main portion 

 of the chips, after alkali extraction and washing, 

 was returned to the digester for the soda cook. 

 Caustic soda solution was added to cover the chips 

 and provide amounts of NasO varying from 15 to 

 35 per cent of the weight of the wood. 



A gage reading of 100 pounds was reached in 

 1-1J hours. The pressure was held at this arbitr- 

 ary value for about three hours to obtain satis- 

 factory disintegration of the wood. The prelimin- 

 ary treatment had already dissolved some of the 

 lignin, so the final cooking was comparatively 

 short. 



The contents of the digester were agitated by 

 stirring frequently. Distillation was carried on at 

 intervals to detect any further evolution of turpen- 

 tine. Only a few drops were obtained, except in 

 those cases where preliminary extraction of the 

 rosin had been incomplete. 



At the end of the cook the pressure was drawn 

 down, the hot liquor drained off and the pulp 

 washed thoroughly. To determine the yield, the 

 pulp was pressed, carefully sampled, and the 

 aliquot portion dried at 105C. 



The pulp was refined in the beater, samples 

 being taken at intervals and made into hand sheets. 



Outline of Experiments 



Experiment 1 served primarily to standardize 

 the apparatus. 2,000 grams of wood and 7,000 c.c. 



31 



