39 



RECOVERY OF CERTAIN WOOD PRODUCTS BY TREATMENT WITH 



CHEMICALS. 



In addition to the distillation methods already mentioned resinous 

 woods may be treated by other processes for the recovery of the tur- 

 pentine and rosin which they contain. For various reasons these 

 processes have received but little attention in the past. Their suc- 

 cessful operation requires more chemical and technical knowledge, 

 and a more extensive plant than the methods commonly employed 

 in recovering turpentine and rosin. Heretofore the value of the 

 products, some of which were not utilized, did not justify the greater 

 cost of these processes. However, as a good grade of light wood con- 

 tains from 15 to 30 per cent of rosin and turpentine which may be 

 recovered by chemical treatment, and as the extracted wood is suit- 

 able for paper making, present prices justify a brief consideration of 

 these processes. 



TREATMENT WITH SODA, SODA ASH, OR VOLATILE SOLVENTS. 



When woods are treated with boiling alkali solutions, with or with- 

 out pressure, turpentine is volatilized, and rosin is dissolved together 

 with other noncellulose matter. The turpentine distils off and the dis- 

 solved matter may be subsequently washed out and recovered as a 

 soap, in which form it may be used as sizing material for paper and 

 in making soap, or the alkali resinate may be thrown out of solution 

 by neutralization and recovered as an impure rosin. In either case 

 the rosin or resinate may be destructively distilled, if desired, for the 

 preparation of rosin spirits and rosin oils. By burning the residue in 

 the retort in a current of air, black ash, an impure alkali carbonate, is 

 recovered, which may be used again for the extraction of turpentine 

 and rosin. Rosin and turpentine may be recovered in the manufac- 

 ture of paper pulp from pine wood by this treatment. 



It has been proposed to recover turpentine and rosin by extracting 

 the finely chipped wood with a volatile solvent, such as benzine, 

 alcohol, etc. In this case the rosin and turpentine obtained are of 

 exceptional purity, but the practicability of recovering the solvent 

 economically remains to be demonstrated. This process also involves 

 considerable risk from fire. 



Both processes are particularly suited to the treatment of sawdust 

 and other finely prepared waste wood, which are destructively distilled 

 only with great difficulty. Both of these methods for the recovery 

 of turpentine and rosin are now being investigated in this laboratory 

 for the purpose of determining their value as industrial processes. As 

 far as is known turpentine and rosin are not recovered with volatile 

 solvents in actual practice, 



[Cir. 36] 



