26 



WOOD TURPENTINE. 



cheaper, but the latter is somewhat more efficient. Stills of the type 

 shown in figures 1 and 2 are known as periodic; that is, they are not] 

 operated continuously, buc distillation is discontinued from time toi 

 time, the residues emptied out, and the still recharged for another 

 distillation. By careful and intelligent operation crude wood tur- 

 pentine can be separated into three or four products of fairly definite 

 proportions, each one passing in succession through the column and 

 being condensed and stored in the proper receiving tank. It is 



FIG. 3. An ordinary continuous beer 

 still used for turpentine distillation. 



FIG. 4. A continuous still with hooded 

 plates. 



preferable, however, to distill the wood turpentine through the column 

 and the pine oils from a pot still, to which they are run from the 

 bottom of the column still. Pine oils distill so slowly with steam 

 that the use of a fractionating column in their case is not practicable. 

 Periodic column stills are suitable only for small plants producing 

 less than 600 or 800 gallons of crude oils per day, in which case the 

 volume of the products does not warrant the installation of the more 

 costly continuous still for the separation of three or more products 

 simultaneously. 



