The Uses of Wood 



way provided from the pit leads the oozing resin to the barrels. 

 After a week or more this pine tar begins to flow and continues 

 /or several weeks. The quality is much lower than that produced 

 in retorts, for it is mixed with dirt. Boiling down pine tar until 

 it loses one-third its weight makes a sticky mass called pitch. 

 The wood in the pit is transformed into charcoal. 



This pit method of extracting tar and making charcoal is a 

 crude prototype of the process of dry or destructive distillation 

 of wood. 



The Dry-Distillaiion Process.— Whdit the oil mill is to the 

 cotton field the still is to the forest. Its work is to dispose of the 

 refuse and to turn it into gold. Crooked branches, knots, root 

 stubs — sound wood the lumberman ignores — is cut up and 

 packed into a retort. A furnace underneath heats this air-tight 

 chamber to 6oo°-8oo° F. The water goes off as steam in a coil or 

 worm, upon which cold water is played in order to cool and condense 

 its contents. A wood gas is next driven off. Then a brownish 

 liquid flows out. This contains wood vinegar, used extensively 

 in dyeworks, and acetic acid, which is made into vinegar. There 

 is also present wood alcohol, useful to the manufacturing chemist, 

 and in many other industries. Tar and creosote are also 

 yielded by maple, beech, and birch, the preferred woods at 

 the regular acid mills. After twelve hours, the retort is 

 emptied and refilled. The wood is found to be transformed 

 into charcoal. Many acid mills are located in New York and 

 Pennsylvania. 



In the longleaf pine woods the crooked, knotty top stuff and 

 root stubs are the richest in resin. These yield in distillation 

 the greatest quantity of tar and turpentine and the highest 

 qualities of these products, also the best charcoal. Beside this 

 process the old method of burning the wood in kilns or pits in 

 hillsides and ladling the tar into barrels was most slovenly and 

 wasteful. Many valuable volatile substances that are now 

 captured in the coil formerly escaped in smoke. 



The most remarkable invention is a method by which ethyl- 

 alcohol, the highest grade known, is derived by distillation from 

 sawdust, and an equally high grade of charcoal is left. It is 

 the Classen method, introduced from Germany a year ago, and it 

 promises to utilise the greatest nuisances of the sawmill, the 

 sawdust and slabs. 



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