DISTILLATION OF STUMPWOOD. 29 
came so violent when a temperature of about 300° C. was reached that 
the distillation could practically be completed without further heat- 
ing, and in less time than the richer wood with continued heating. 
It was necessary, therefore, in distilling the “ bull pine” to watch 
the oil-bath thermometer carefully in running up the temperature 
for destructive distillation and turn off the heater flame when this 
period was reached. ‘The reaction progresses so rapidly that the dis- 
charge of gas and vapors may exceed the otherwise ample condenser 
capacity, and loss of distillate result from imperfect condensation. 
The difference in behavior is due to the fact that the richer wood con- 
tains a much greater ratio of rosin to cellulose. The heat set free 
during decomposition of the wood substance is more than offset by 
that required to effect decomposition of the rosin in such wood, and 
additional heat. must be supplied to insure the decomposition of rosin 
and the distillation of the products. 
_ The fact that in the destructive distillation of nonresinous woods 
enough heat above a certain temperature is developed to complete the 
distillation without the application of heat from outside sources, 
necessitates the installation of larger condensers in the distillation 
of nonresinous woods than are needed in the distillation of resinous 
woods. When the exothermal reaction begins, it proceeds so rapidly 
that the condensers, which in the earlier stages were large enough to 
condense all condensable material, can no longer do so, and a loss of 
valuable products occurs if the condensers are too small to meet all 
the requirements that may be placed upon them during the exother- 
mal period. 
YIELDS. 
The yields of crude products obtained in the retort distillation, and 
of the refined turpentine and pine oil for each sample, are given in 
Table 14. A summary of these tabulations, giving the average re- 
covery from the various grades of wood distilled, is given in Table 19. 
