APPLICATION OF RESULTS. 31 



oil. It can be seen that there should be a certain combination of values- 

 for these variables which would give the most economical method of 

 operation for a steam distillation plant; but there are other factors 

 which must be taken into consideration in determining the proper 

 combination of values. For example, the best size of the chip will not 

 be determined entirely by the effect of size on yield and efficiency, but 

 also by the relative costs of preparing different sized chips and the use 

 to which the chips are to be put after steaming; the best pressure of 

 steam will not be determined entirely by the effect of pressure on 

 yield and efficiency, but also by the relative costs of high and low 

 pressure steam and of apparatus for various pressures ; the best speed 

 for the distillation will not depend entirely upon the effect of speed 

 on the yield of products and on the amount of steam required, but 

 also upon the cost of steam and the overhead charges; the best end 

 point at which to stop the distillation will not depend entirely upon 

 the effect of end point on yield and efficiency, but also upon the cost 

 of the raw material and the value of the products. 



With the experimental data given, however, and with a knowledge 

 of the various cost factors, which would naturally differ widely in 

 different plants, it will be possible to decide readily on the most 

 economical methods of operating. 



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