YIELDS FROM DISTILLATION OF CERTAIN HARDWOODS. 



TABLE 1. Sample data sheet. 



Shipment No. 197. 



Sample Nos. 21 and 22. 



January 14. 1913. 



Actual wei.eht of charge 09.86 pounds. 



Dry weight of charge I'M. 10 pounds. 



Project No. 152. 



Run No. 97. 



Birch slab wood. 



10 per cent to 14 per cent bark. 



Total distillate= 32.83 pounds. 



COLLECTION AND ANALYSIS OF PRODUCTS. 



A typical data sheet is' shown in Table 1. The time and tempera- 

 tures were read as every liter or half liter of distillate was collected. 

 In a few distillations separate titrations for acetic acid were made 

 on the first several fractions of one-half liter or one liter each, but in 

 general all the distillate was mixed for analysis. 1 The distillate was 

 allowed to settle for at least 24 hours. At the end of that time the tar 

 and pyroligneous acid were separated by decantation, and the vol- 

 ume and weight of each determined. The charcoal was allowed to 

 cool in the retort over night, and was weighed after separation from 

 the "tar coke." Tar coke refers to the material occurring in the 

 retort that was clearly a residue from the distillation of tar. This 

 was weighed separately. The gas was computed by difference, and 

 no determination of its composition was made. 



PYROLIGNEOUS ACID. 



The pyroligneous acid was analyzed by the methods described by 

 Klar 2 for the determination of acetic acid, wood alcohol, and dis- 



1 The acetic acid in that part of the distillate (consisting usually of water) which came over before true 

 destructive distillation began amounted to from 8 to 10 per cent of the total acetic acid; the alcohol in the 

 same part amounted to about 1 per cent of the total alcohol. The volatile acids obtained at temperatures 

 below the point at which the wood begins to distill destructively, say 280 C., must have an origin differ- 

 ent from that of the acid obtained during the destructive distillation. It is probably formed by action of 

 the water on the wood fiber at high temperatures similarly to the acid obtained by hydrolysis as reported 

 by Cross (Dissertation, Gottingen, 1910). 



8 Technologic der Holzverkohlung, p. 337. 



