6 BULLETIN 983, U. S. DEPARTMENT OF AGRICULTURE. 
market for it. In addition, the waste as it comes from the mill is 
usually a mixture of all forms, and any attempt at separation, except 
perhaps a simple blowing or screening to remove the very fine stuff, 
will increase the cost of the raw material to a prohibitive figure. 
Therefore, in any satisfactory process for the utilization of mill waste, 
it must be possible to handle any and all forms of waste as it comes 
from the mill. 
Except in factories using only one or two species of wood, or in mills 
cutting only a few similar species, such as the " yellow pine" (long- 
leaf, shortleaf, and loblolly) of the South, the differences in quality 
and form of the waste have operated against its efficient utilization. 
This is because many processes, such as pulp and paper making or 
destructive distillation, require a particular species in order to give a 
yield and quality of product that will make the processes commercially 
feasible. 
Woods of all species and forms, however, have one point in com- 
mon — they all contain more or less cellulose, which makes up the 
fibers of the wood, along with an incrusting substance called lignin. 
A chemical utilization of this cellulose would overcome the objec- 
tions stated above as to the form of the material, length of the fiber, 
and species, provided the amount of cellulose present was sufficient 
to give a yield of alcohol that could be handled profitably on a com- 
mercial scale. 
PROCESSES FOR THE MANUFACTURE OF ALCOHOL FROM WOOD. 
The processes used for the production of ethyl alcohol from wood 
may be grouped into two general classes: Hydrolysis of wood into 
fermentable sugars by the use of dilute acid (preferably mineral acid) 
as a catalyzer, and solution processes, in which the wood is dissolved 
in concentrated acid and the diluted solution is then subjected to 
hydrolysis. 
The first process consists, in general, of digesting sawdust or hogged 
and shredded wood with a dilute mineral acid under 60 pounds or 
more of steam pressure. This converts part of the wood into a 
mixture of pentose and hexose sugars. The latter are then fermented 
into ethyl alcohol. 
Processes of the second class, involving the use of concentrated 
sulphuric acid and in which the wood is actually dissolved by the 
acid, as in the Ekstrom 5 process, have not received commercial 
attention, notwithstanding the fact that Flechsig 6 many years ago 
showed that cotton cellulose could thereby be converted into dex- 
trose and alcohol almost quantitatively. The more recent work of 
s French Patent No. 380358; German Patents Nos. 193112 and 207354. 
s Zeit. fur Physiol, chemie., 1882. 
