158 A ppendia 
Woop DistTitLatTion 
Valuable commerciat products are obtained through wood 
distillation by two distinct processes, destructive distillation. 
and steam distillation. In the former process the wood fiber 
is broken down and charred and new compounds are formed, 
while in the steam process the wood retains its original form. 
In destructive distillation direct heat is applied below the 
vessel containing the wood and the heat vaporizes the volatile 
compounds, such as turpentine, and breaks down the non- 
volatile compounds, such as wood gums, and forms a number 
of new compounds, leaving a residue of charcoal. The 
decomposition of wood in this process is complicated and not 
yet fully understood. 
In obtaining the products from steam distillation the process 
is simpler. The wood is chipped and placed in a closed recep- 
tacle into which steam is blown from a boiler, and the volatile 
compounds are vaporized and carried out of the retort with 
the steam. Although the wood is at times so much overheated 
that its fiber is slightly decomposed, it is substantially correct 
to say that in steam distillation there is no decomposition of 
the wood fiber, while in the destructive distillation the fiber 
is destroyed. In the one process the wood is only steamed, 
while in the other the wood is charred or burned. 
As there are two different processes of obtaining distillates, 
so there are two different classes of products obtainable from 
the various woods. The hardwoods, for example, such as beech, 
birch, and maple, yield acetic acid, wood alcohol and charcoal ; 
while the softwoods, such as longleaf pine, yield turpentine, 
tar, oils and charcoal. This difference in the products is due 
to the fact that pine woods are resinous, while hardwoods are 
non-resinous. 
New York is not within the softwood distillation area. 
Hardwood distillation plants are found principally in New 
York, Pennsylvania, and Michigan, where an adequate supply 
of beech, birch, and maple is available. These three woods 
produce nearly all of the commercial products. The Forest 
