value of the rosin fraction. Incineration of the 

 waste pulping liquor provides for the recovery of 

 the balance of the alkali, within the practical 

 limits of mechanical efficiency. 



As mentioned before, practical application of 

 this treatment of the more resinous materials 

 could be carried on most conveniently as a supple- 

 ment to ordinary pulp-mill operations on lean wood. 

 Only slight modifications in certain of the existing 

 digester units would be necessary to take care of 

 the richer grades of pine. The supply of fat wood 

 could be obtained by sorting the raw material 

 received at the pulp mill or by procuring lightwood, 

 etc., from independent sources. 



There is also a possibility that the first stage of 

 the process, namely that of extraction with caustic 

 soda or sodium carbonate, could be employed in 

 treating those grades of resinous waste which 

 would not lend themselves to final pulping. Charred 

 or unsound wood might be steamed with dilute 

 alkali for the recovery of rosin and turpentine, 

 without provision for treatment of the extracted 

 chips. The economic merits of such a scheme 

 could be decided only by actual trial. 



52 



