CONCLUSIONS. 55 



Preferably a globe-shaped digester revolved on hollow trunnions 

 should be used. The cooking liquor and steam are fed through one 

 trunnion while the steam carrying the volatile oils is removed through 

 the other. When the oils practically cease to come over the valve 

 in the take-off trunnion is closed and the wood cooked at the proper 

 pressure. 



Suitable equipment for a plant making steam wood turpentine and 

 using 50 cords of wood per day consists of two 8-cord rotary digesters, 

 a total boiler capacity of 450 horsepower, engine capacity of 250 

 horsepower, a hog, a shredder, conveyers, condensers, refining stills, 

 storage tanks, pumps, piping, and building. The whole will cost 

 between $35,000 and $50,000. 



REFINING. 



Steam and crude oil vapors should not be condensed together before 

 refining, as this calls for unnecessary apparatus and the increased 

 steam consumption makes the operating expenses larger. The 

 vapors should be so handled as to separate the light oil with some 

 heavy oil from most of the heavy oils and the water. For refining 

 1,000 or more gallons of crude oils per day a continuous column still 

 should be used, large enough to take care of the volume of steam 

 entering it, and so constructed that two, and possibly three, distinct 

 products may be obtained. Each column should be so arranged 

 that its contents can not be carried forward to the column containing 

 the lighter oils, but the residues from the fraction-ation in one column 

 may pass to the next lower one from which heavier oils are obtained 

 and so on until the condensed water is practically freed from oils and 

 goes to waste from the bottom of the last column. Stills of this 

 character can be built, and while their first cost is high, they insure, 

 when properly constructed and operated, the separation of fairly 

 uniform products. 



The experiments made in this laboratory also show that in order 

 to obtain a wood turpentine, which will comply in specific gravity, 

 refractive index, evaporation, and behavior on distillation with gum 

 spirits, it is necessary that the heavier oils be removed from contact 

 with live steam as rapidly and as completely as possible. To this 

 end the fractionating plates should carry the minimum depth of 

 liquid and the steam should not be allowed to continue to pass 

 through the heavy oils after they have been freed from the light oils. 

 The hot heavy oils pass downward to other fractionating chambers, 

 each of which may be operated to yield a fairly definite product, or 

 they may be refined in a pot stifl. The general character of the 

 products obtained with the column still is shown in Tables 4 to 8, 

 pages 62 to 66. 



