20 



12 show the general arrangement of plants. The separation and puri- 

 fication of the products will be described under the several products. 



FIG. 12. Plan of German type of fractional distillation plant: A, reservoir for settling pyroligneous 

 acid; B\, tar still; Bi, Bz, liming stills; C, vat for filtered acetate liquor; D, reservoir for crude 

 dilute alcohol; E, filter press for acetate liquor : F\,F->, f 3, vats for unfiltered acetate liquor; Oi,Gz, 

 evaporating pans for acetate; Hi, Hz, Hs, column rectifying still for concentrating alcohol; L, 

 milk of lime vat; M, boiled tar car. 



NATURE OF THE REACTIONS IN THE RETORT. 



When hardwood is heated decomposition does not begin until the 

 temperature has reached 150 C., the loss below this temperature 

 being water alone. With resinous woods turpentine begins to distil 

 with water at 97 C. and continues to pass up to about 185 C., over- 

 lapping with such products of destructive distillation as may begin to 

 pass over above 150 C. Above this temperature (150) a liquid prod- 

 ucts resulting from the decomposition of the wood are distilled. The 

 total quantity volatilized, as determined by Violetti, from moisture- 

 free hardwood at different temperatures is shown in the following 



table: 



Percentage of wood volatilized at different temperatures ( Violetti). 



alt is very doubtful whether alcohol, acid, or tar begins to distil before the temperature of the 

 retort reaches 200 C. 

 [Cir. 36] 



