60 



THE WORK OF triS FObESt DEtAJltMENt IN tiSTDtA. 



gases, connected with a system of separating condensers and 

 receivers for tar, pyroligneous distillates and gases. Complete 

 control over the temperature of distillation is secured. Heating 

 wood in small retorts at a high temperature gives much gas and 

 little charcoal, acetic acid and tar, while slow heating in larger 

 retorts gives an increased yield of acetic acid and charcoal. For 

 the production of acetates and wood alcohol, hard woods are 

 more suitable than resinous woods, which yield principally tar 

 and wood oils. The dry distillation of wood is one of the 

 principal forest industries in Europe and America. The 

 capital invested in the industry in Europe alone exceeds 

 £40,000,000. In France about 98,000 cords of beech and oak 

 are employed for distillation (a cord = 125 cubic feet). 



Before the present war Germany showed the greatest 

 production, owing to the development of chemical industries 

 which consume large quantities of acetic acid. America is 

 another large producer. 



The yields of products per cord are : — 



Charcoal, 



in 

 bushels. 



Hard woods 

 Resinous woods 

 Saw dnst 



4,0—50 

 25—40 

 2S— 35 



Alcohol, 



in 

 gallons. 



8-12 

 2—4 

 2—4 



Calcium 

 acetate, 

 in lbs. 



150—200 

 50-100 

 45—75 



Tar, in 

 gallons. 



8—20 

 30—60 



Wood 



oil, in 



gallons. 



30—60 



Turpentine, in 

 gallons. 



r heavy woods 12 — 2 

 (.light woods 2— 10. 



The chief products of dry distillation are: — 



(1) Wood gases which are employed as fuel. 



(2) Pyroligneous acid containing wood alcohol and acetic 



acid. 



(3) Wood tar. 



(4) Charcoal. 



The following are the principal uses of the different 

 products : — 



Charcoal is used for the production of pig-iron in blast 

 furnaces, in copper and sugar refineries, in the 

 manufacture of gunpowder and for fuel. 



