16 



BULLETIN 129, U. S. DEPARTMENT OF AGRICULTURE. 



high carbon content or high crushing strength is required it might 

 not be suitable. 



The yields of tar are also somewhat higher than those usually 

 obtained in practice, and this can not be explained entirely by the 

 low maximum temperature of distillation, since further distillation 

 of the charcoal at higher temperatures gave increased production of 

 tar. (See p. 4.) It is probable, however, that under the experi- 

 mental conditions of distillation there was less tar decomposed into 

 gas and coke than under commercial conditions where part of the 

 tar would be subjected to considerably higher temperatures after 

 formation. 



TABLE 9. Average yields per cord of pyroligneous acid, charcoal, and tar from various 



species. 1 



PYROLIGNEOUS ACID (MINUS MOISTURE). 



CHARCOAL. 



TOTAL TAR. 



1 The weights per cord were derived as explained on p. 6. 



WASHINGTON I GOVERNMENT PRINTING OFFICE ; 1914 



