THE MADISON WOOD-SUGAR PROCESS 

June 1946 

No. R1617 

UNITED STATES DEPARTMENT OFAGRICULTURE 

FOREST SERVICE 

FOREST PRODUCTS LABORATORY 

Madison, Wisconsin 

In Cooperation with the University of Wisconsin 
1 

THE MADISON WOOD-SUGAR PROCESS 

By 

ELWIN E. HARRIS, Chemist 

and 

EDWARD BEGLIUGER , Chemist 

Forest Products Laboratory, 2 Forest Service 

U. S. Department of Agriculture 

Abstract 

A process, known as the Madison wood-sugar process, has been developed 

by the Forest Products Laboratory for hydrolyzing mixtures of wood waste 

consisting of chipped slabs and edgings, sawdust, and shavings, with 0.5 to 

0.6 percent sulfuric acid at temperatures of 150° to 180° C. by allowing the 

dilute acid to flow continuously through the charge of wood. 

Compared with the German Scholler process, hydrolysis was accomplished 

in less time because the sugars produced by the hydrolysis were removed more 

rapidly. Heating was at a lower rate and more efficient use could be made 

of the heat given off by the liquors being removed from the hydrolyzer, resulting in a lower steam requirement. Decomposition was less because the 

sugars were in contact with the acid for a shorter period of time and, consequently, yields of sugar and alcohol were higher. Fewer byproducts 

inhibitory to fermentation wore produced, resulting in more rapid formentations. Life of valves and other equipment was increased because they were 

set once for the run and not changed until the end of the run. The sugar

produced in 2.8 hours from a ton of dry, bark-free Douglas-fir wood waste 

yielded 64.5 gallons of 95 percent alcohol as compared to 3.2 hours for 

58 gallons by the rapid-cycle method developed earlier, and 13 to 20 hours 

for 55 gallons by the Scholler process as practiced in Germany. 

These new findings indicate that the estimated capacity of the woodhydrolysis plant being built at Springfield, Oregon, may be increased from 

4,100,000 gallons per year to 5,950,000 gallons per year, 

1Presented before the American Chemical Society, Atlantic City, N. J., 

April 8-11, 1946. 

2 

Maintained at Madison 5, Wis., in cooperation with the University of 

Wisconsin. 

Report No. R1617 -1-
Introduction 

Previously reported work (4, 7, 15, 33)

3 on wood saccharification has 

shown that many of the steps in the process described by Scholler (1-3, 2, 

6, 9-14, 16, 20, 32) are unnecessary and detrimental, and are responsible 

for making the German Scholler process unsuited for use in the United States. 

The batch process, as used by Scholler for the treatment of the charge of 

wood in the hydrolyzer, is responsible for the long periods of time required 

(16 to 20 hours), for low concentrations of reducing sugars, and for excessive consumption of chemicals. The steaming and rest periods between batches 

of acid promote the decomposition of sugar (17), cause a great deal of 

unnecessary manipulation of controls, and contribute to a short life for 

valves and other essential parts of the plant. This report describes a new 

short process which includes (1) a procedure for charging the digester: (2) 

a method of automatically controlled continuous addition of the acid at the 

top of the digester; (3) controlled removal of sugar solution from the bottom; 

(4) controlled hydrolysis to avoid decomposition and lignin plugs; (5) flashing the solution to a definite pressure so that methanol and furfural produced 

in the process may be recovered and excess steam may be used for heating of 

water; (6) neutralizing automatically under pressure; (7) filtering under 

pressure to remove calcium sulfate; (8) flash cooling of the sugar solution; 

and (9) filtering again to remove organic precipitate that separates on 

cooling. 

Pilot-plant Equipment 

The equipment, shown diagrammatically in figure 1, consists of a hog 

chipper for converting wood waste to the proper size for hydrolysis; elevating equipment; a triplex pump for water (capacity variable from 2 to 10 

gallons per minute); and. acid pump (capacity variable from 0.2 to 4 gallons 

per hour): a switch, on the valve that 'opens the line to the hydrolyzer, 

which controls both pumps; a water heater consisting of a jet heater for 

blowing steam into the water; a jet in the water line for introducing acid: 

two openings in the top of the digester for introducing acid liquor: a 

silicon bronze digester 23 inches in inside diameter (capacity 27 cubic 

feet) fitted with a reducing cone at the top and a reducing cone and filter 

screen at the bottom; a flash tank; three receiving tanks fitted with mixers; 

a lignin receiver; a neutralizing kettle; and storage tanks, 

Analysis 

Analytical values were determined by the methods reported upon previously by the Forest Products Laboratory (4, 18, 19). 

3 Underlined numbers in parentheses refer to Literature Cited at the end of 

this report. 

Report No. R1617 -2-
The Process 

Chipping or hogging; is an important part of the process. Particles 

should be large enough so that flow of dilute acid down through the charge 

is uniform and rapid, but also small enough so that diffusion of the acid 

into the chip and of the sugar out of the chip is rapid. It was found that 

Douglas-fir wood-waste mixtures, containing 25 to 30 percent shavings, 25 

to 30 percent sawdust, and 40 to 50 percent slabs and edgings, hogged so 

that particles were between 1/4 and 1 inch long, were satisfactory. The 

hogged wood contained 35 to 50 percent bark. A hog chipper provided satis­ factory material when the larger sizes were screened out and sent through 

again. Green wood waste containing 30 to 50 percent of its weight as moisture appeared more satisfactory than dry material because infusion of acid 

was more rapid. 

Charging of the digester had to be carried out so that the wood waste 

was evenly distributed in respect to fine and coarse material, was uniformly 

packed, and was of such a density that full use of the acid as a hydrolyzing 

and extracting medium was reached and so that plugging of the digester did 

not result. Variations in the amount of bark made possible variations in 

the extent of packing of the charge. Because of the corky nature of bark, 

charges with large amounts of bark could be packed more heavily into the 

digester without plugging it. It proved helpful but not essential to place some coarse material on the bottom of the digester to provide a bed for 

easy flow of the sugar solution through the filtering screen at the bottom 

of the digester. These conditions were attained when a charge of mixed 

wood waste was allowed to flow into the heated hydrolyzer until completely 

full, after which a quick opening flange cover was put in place and highpressure steam (150 pounds per square inch) was applied rapidly on top of 

the charge, with vents open at the bottom until a gage at the top of the 

digester showed a pressure of 10 pounds. The steam valve was then closed 

and the steam allowed to flow through the charge until no pressure showed 

on the gage. The cover was then removed, more of the wood-waste mixture 

added, and the packing with steam repeated. Charges of 400 to 500 pounds 

on a dry basis with 25 to 35 percent of bark were introduced under these 

conditions. The heavier charges were used when the largest amount of bark 

was present. Most of the air in the chips was removed, and some heating 

resulted, as the steam passed over the chips. In order to remove more air 

and to continue the heating, a top vent was opened and steam was introduced 

at the bottom of the digester. When steam flowed from the top vent, the 

vent was closed and the steam was allowed to flow into the digester until a 

pressure of 50 pounds was reached. 

Dilute acid at a temperature of 150° C. was introduced into the 

heated digester in such concentrations that, by the time an amount of dilute 

acid equivalent to one-half the dry weight of the charge had been introduced, 

the acid concentration of all the water present would be 0.5 to 0.6 percent. 

A charge of wood waste containing 45 percent of its weight as moisture, 

after being packed and heated with steam at 50 pounds per square inch, contained approximately 600 pounds of moisture and therefore required 200 

pounds of 2.0 percent sulfuric acid to bring the concentration to 0.5 percent. 

Report No. R1617 -3-
After this stronger acid had been introduced, sufficient heated sulfuric 

acid of 0.5 to 0.6 percent concentration was introduced to bring the ratio 

of total dilute acid to dry wood substance to about 3 parts acid and 1 part 

wood substance. Under one set of conditions, this acid was introduced 

rapidly, so as to flood the charge, and then allowed to digest for approximately 20 minutes. Under another set of conditions, tho acid was pumped in 

at the rate of 20 pounds per minute. 

Following this initial charge, heated acid (concentration 0.5 to 0.6 

percent) was pumped in continuously at a rate of 20 pounds per minute. The 

temperature of the incoming acid was adjusted by an automatic temperature 

controller so that it was increased approximately 5° C. for each 10-minute 

period until 185° C. was reached; the run was continued at that temperature 

until completed. This procedure was also compared with the batch procedure 

for introducing acid used in previous runs (7). 

While the continuous pumping was in progress, a flow controller in 

the acid-sugar-solution line was opened so that 20 to 25 pounds of the solution of acid and sugar were removed per minute. 

The continuous introduction of acid and continuous removal of sugar 

solution provided a means of rapid hydrolysis and removal of the solution. 

Initial concentrations of reducing sugar were as high as 10 percent. Concentrations decreased as the hydrolysis continued. After about 2 hours of 

continuous pumping, the concentration fell to about 1 percent, and at this 

point the introduction of acid was stopped, Sugar solution was removed as 

long as it flowed freely from the hydrolyzer. In most cases it continued to 

flow for about 15 minutes, after which a large valve in the bottom of the 

digester was opened to discharge the lignin into a lignin receiver. 

The sugar solution being withdrawn from the hydrolyzer vas passed 

into an expansion chamber of "flash tank" to release the steam and drop the 

pressure to about 30 pounds per square inch. The drop in pressure was 

accomplished by a pressure-regulating relief valve which allowed the steam 

and the vapors of methanol and furfural to pass through a heat exchanger or 

condenser, in which they gave up heat which was used to heat the water for 

the dilute acid. 

From the flash tank the sugar solution flowed continuously under a 

pressure of 30 pounds per square inch to a pressure-neutralizing tank (fig. 

2) at the rate of 16 to 20 pounds per minute. When approximately 100 

pounds of solution had flowed into the tank, the automatic pH controller 

was started, lime being thereby introduced under air pressure from a lime 

tank through a proportioning valve. The controller was actuated by a stream 

of liquid, which was removed from the neutralizing tank and flashed to 

atmospheric pressure and then allowed to flow over the electrodes in a 

specially designed cell. The amount of solution required was approximately 

100 cubic centimeters per minute. This sugar solution was collected and 

introduced in the neutralizing kettle prior to the next run. When thepH 

of the solution in the neutralizing kettle had reached the desired value, a 

valve to the filter was opened, allowing the same amount of solution to be 

Report No. R1617 -4-
removed as introduced. Variations in pH were usually less than 0.1 pH units 

during the neutralization of the sugar solution for a run requiring about 3 

hours. 

Attempts were made to neutralize the sugar solution continuously in 

a pipe line at atmospheric pressure without the use of a holding tank. The 

lag in the neutralization with lime was too great to permit satisfactory 

operation of tho pH controller. Tests with sodium hydroxide gave satisfactory operation. 

Neutralization of the sugar solution under pressure in batches was 

carried out satisfactorily with the same equipment used for continuous neutralization. Such batch neutralization, however, required either the use 

of a holding tank to store the solution under pressure or the flashing of 

the acid-sugar solution to atmospheric pressure before storage, followed by 

reheating of the solution before it could be neutralized and filtered. 

The calcium sulfate, which had separated from the solution under 

pressure, was removed by passing the solution while under pressure through 

a steam-jacketed leaf filter. The sulfate content, which would have been 

2,100 parts per million at 100° C. and atmospheric pressure, was reduced to 

an average of about 650 parts per million by neutralizing and filtering it 

under a steam pressure of 30 pounds per square inch. This low value for 

calcium is expected to aid greatly in preventing scale formation in the 

stills during the alcohol distillation. 

After being filtered under pressure, the neutralized sugar solutions 

were cooled to a temperature of 30° C. by flashing. On cooling, a brown 

precipitate separated from the solution. When this precipitate was removed, 

the solution was a clear amber color and contained approximately 5 percent 

reducing sugar. 

The procedure described as the "Madison Wood-sugar Process" was used 

to hydrolyze the carbohydrate portion of Douglas-fir wood waste from sawmills operating in the Eugene, Oregon, area. Representative samples of bark, 

bark-free hogged slabs, hogged mill-run slabs and edgings, shavings, sawdust 

and hogged mill waste from which the best slabs had been removed were analyzed 

for bark content, potential sugar content, and potential fermentable sugar 

content, and then subjected to the pilot-plant batch hydrolysis procedure 

described in previous Forest Products Laboratory reports (4, 7). 

Two sets of conditions were employed. In one, the hydrolysis was 

continued until the concentration of the sugar being removed was 0.5 percent or less. In the other, the hydrolysis was continued until the average 

redwing-sugar content of the total hydrolyzate was approximately 5.0 percent. In tho case of bark, the latter hydrolysis was discontinued when the 

concentration of the reducing sugar being removed was 1.0 percent or less, 

because at no time was the concentration of reducing sugar from bark as 

high as 5.0 percent. The values for the analysis, hydrolysis, and yields 

of alcohol from the various samples are given in table 1. 

Report No. R1617 -5-
-- 

The yield of alcohol from bark was so low that the capacity of the 

hydrolyzer equipment to produce fermentable sugar was lessened. In order 

to increase this capacity, several tests were made in which either larger 

quantities of wood waste were charged into the digester by using higher 

packing pressures, or shavings or hogged bark-free slab wood were mixed 

with the hogged mill waste to reduce the average bark content of the total 

charge. In these tests, in which about 25 percent of the charge was bark, 

about 7 percent of the total alcohol obtained was from the bark. In order 

to have a uniform basis for comparison, however, the yields of reducing 

sugar and alcohol are expressed on the basis of bark-free wood. Table 2 

gives the values for the wood waste containing varying amounts of bark and 

hydrolyzed by batch addition of the dilute acid and batch removal of the 

sugar solution. 

Because of the greater case of operation and control afforded by the 

method, several tests were made in which acid was continuously introduced 

and sugar solution continuously removed throughout the entire hydrolysis 

period. In most cases sugar solution began to flow from the bottom of the 

hydrolyzer about 15 minutes after the acid was first introduced. In many 

cases, the first sugar solutions to come off were only partially hydrolyzed. 

Values for the hydrolysis of wood obtained with the completely continuous 

process are given in table 3. Hydrolysis was discontined when the average 

concentration of reducing sugar of the total hydrolyzate was approximately 

5.0 percent. 

In order to overcome the tendency toward only partial hydrolyzation 

of the first reducing sugar removed, the following changes in pocedure were 

made: (1) 200 pounds of dilute acid 1.5 to 2 percent concontration -

was rapidly introduced; (2) 400 to 600 pounds, or the amount of acid of 0.5 

to 0.6 percent concentration required to bring the ratio of dilute acid to 

wood to 3 to 1, was introduced at a rate of about 12 gallons per minute; 

(3) the reaction was allowed to continue for 30 minutes from the time the 

first acid was introduced, meanwhile maintaining the temperature at 150° C. 

by admitting steam at the bottom of the digester; (4) after this reaction 

period, the pumps were set to introduce 20 pounds of acid (0.5 to 0.6 percent solution) per minute and the temperature controller was set to increase 

the temperature 0.5° per minute until a temperature of 185° C. was reached, 

at which the run was continued until completed. The sugar solution was 

removed continuously through a flow controller at the same rate the acid 

was introduced. The hydrolysis was discontinued when the average reducing 

sugar concentration of the total hydrolyzate was about 5.0 percent. The 

solutions were neutralized under pressure with lime, cooled to 30° C., 

adjusted for pH to the final desired value, and then fermented. The procedure for fermentation is given in an accompanying report (8). The results 

of these hydrolysis tests and fermentations are given in table 4. 

Report No. R1617 -6-
Discussion 

Assuming that the values in the last 22 runs of table 4 are representative of the charging capacity of the digester and of the mixture of 

wood waste available, an average charge of 319 pounds of dry, bark-free 

wood waste Can bo placed in a 27-cubic-foot digester. This corresponds to a charge of 11.8 pounds of dry, bark-free mixed wood waste per cubic foot. 

Tho average alcohol yield from the sugars produced by hydrolysis corresponded to 64.5 gallons per ton of dry, bark-free wood, or 0.38 gallon per 

cubic foot of digestor space. 

Application of Findings to a Commercial Plant 

These values may be used in determining the capacity of the wood 

hydrolysis plant being constructed by tho Defense Plant Corporation at 

Springfield, Oregon, formerly sponsored by the War Production Board and now 

by the Department of Agriculture. 

The plant consists of 5 digesters, each with a capacity of about 

2,000 cubic feet. Each digester will hold 11.8 tons of dry, bark-free wood, 

or 15.8 tons of the dry wood substance. In most cases moisture constituted 

about 40 percent of the total weight of the material charged into the digester and therefore the usual charge, including moisture, would be about 

26.5 tons. 

Loading equipment and valves are designed to charge and pack the 

digesters in about 30 minutes, and steaming and heating will require about 

another 30 minutes. Assuming the rate of flow of the initial charge of 

acid downward through the bed of chips to be a function of the depth of 

the bed, and the rate per foot traveled to be the same as in the 27-cubicfoot digester, 40 minutes will be required for the liquid to pass through 

the charge in the 2,000-cubic-foot digester instead of the 11 to 12 minutes 

required in the pilot-plant digester. The rate of hydrolysis of the cellu­ lose is a function of acid concentration, time, and temperature (17) and is 

independent of the size of the digester. Since the introduction of the 

acid and removal of the sugar solution are continuous, no extra time need 

be allowed for the flow of hydrolyzing liquid through the charge after the 

run is started and until the pump is stopped, when another 40 minutes will 

be rewired to drain the liquid from the digester. 

The over-all increase in time rewired because of the larger size of 

the commercial digester should therefore be only 55 to 60 minutes. The 

average time required for the last 22 runs listed in table 4 was about 2 

hours and 50 minutes from the time the pumping started until the lignin was 

discharged from the digester. This would indicate that 4 hours should be 

sufficient for the same operation in the large digester and that, including 

the charging of the digester and heating, a 5-hour operating cycle would be 

possible. Such conditions would, of course, allow no time for repairs and 

possible need for removal of some lignin from a digestor. It appears, 

Report No. R1617 -7-
however, that the latter possibility has been removed because, in about 100 

runs using continuous pumping with Douglas-fir mill waste, the equipment 

has never failed to blow the lignin completely from the digester. Even 

allowing an hour for such exigencies, or a 6-hour operating cycle, 20 

charges of wood could be hydrolyzed per day, The yield of alcohol obtained 

in the last 22 runs of table 4 indicates that 760 gallons of alcohol could 

be produced from the sugars from one digester charge or 15,200 gallons per 

24-hour day and 5,472,000 gallons per 360-day year for the whole plant. If 

a 5-1/2-hour cycle is possible, allowing 30 minutes down the per run, the 

output would be 16,550 gallons per day, or 5,950,000 gallons per year, 

For tho production of 15,200 gallons of alcohol per day, 236 tons of 

dry, bark-free wood, or 310 tons of dry wood with bark would be required, 

If the 5-1/2-hour operating schedule is used and 260 tons of dry, bark-free 

wood produce about 16,550 gallons of alcohol per day, 350 tons of dry wood 

substance with bark will be required. 

Automatic control of tho introduction of the acid and removal of the 

sugar solution, as wall as automatic control of neutralization, makes better 

operation possible with less manpower, Improvements in a process for continuous fermentation which will be published in another report make possible 

savings in manpower and better distribution of the use of equipment for that 

portion of the operation also. 

Cost of Production of Alcohol 

There are many unknown factors in the cost of operation of such a 

wood-hydrolysis plant. Assuming the values for chemicals required and the 

yields of products obtained in tho pilot plant as representative of what 

will be possible in a large plant, the cost of chemicals for processing 1 

ton of dry, bark-free wood waste can be tabulated as follows: 

Report No. R1617 -8-
On the basis of a yield of 64.5 gallons per ton of wood the cost of 

chemical per gallon of alcohol produced would be 3.9 cents. 

An average delivered price of $2 per ton of dry, bark-free wood is 

assumed. Wood with bark and with moisture is to be used for the process, 

but since moisture and bark yield very little or no alcohol, the processor 

does not expect to pay for them. The presence of moisture and bark increases 

delivery costs and limits the distance wood waste may be transported. Two 

to 2-1/2 tons of material must be delivered at the plant for each ton of 

dry, bark-free wood. The cost for wood per gallon of alcohol produced on 

this basis is 3.1 cents. 

The calculated labor requirement for the plant is 65 men. On the 

basis of present wage scales and other labor overhead, such as insurance, 

social security, and other expenses, the cost for labor would be 4 cents per 

gallon. 

Other costs such as electric power, water, maintenance, overhead, 

supervision, and extra wood waste that may be needed for the power plant are 

estimated to be 3.7 cents per gallon, 

These values bring the cost of production, exclusive of plant amortization, to 14.7 cents per gallon. No credit is taken in these calculations 

for byproducts. Assuming that it is desirable to pay off as much of the 

cost of the plant as possible while alcohol prices remain high, and allowing 

3 percent interest on the investment. the retirement of tho principal in 

about 4 years for a plant producing 5,472,000 gallons per year would cost 

13.7 cents per gallon. Amortization in 7 years with a production of 

5,950,000 gallons would cost 7.6 cents per gallon, bringing the cost of production to between 22.3 and 28.4 cents per gallon, exclusive of any income 

from byproducts. 

Byproducts of the Process 

The dally by-products of tho process are &out 100 tons of lignin 

(dry basis), 33 tons of calcium sulfate dihydrate, 6,000 pounds of 

5,000 pounds of methanol, and about 11.8 tons of nonfermentable sugars 

dissolved in about 1,800 tons of water. Ready markets are available for 

the furfural and methanol, and income from these products can reduce the 

cost chargeable to tho alcohol. 

Until other markets are developed, it is expected that the lignin 

will be used as boiler fuel. On a dry basis, this lignin has a value of 

about 10,500 B.t.u. per pound. Normally the product will be obtained from 

tho process with about 50.0 percent moisture, The sulfur content due to 

sulfuric acid will be about 0.16 percent. This value may be lowered by 

washing if a lower acid content is desired. It is believed that the lignin 

should supply most of the fuel required. This lignin is being tested as a 

resin extender, for plastics, as a carrier of chemicals for soils improvement, and as a source of new chemical products. If it is found that lignin should have a higher value in some of these or other fields than it has 

as fuel, it. too, may be used to reduce the cost of alcohol. 

Report No. R1617 -9-
Calcium sulfate has value in some localities as a source of lime and 

sulfur for the soils. It is expected that its value for this purpose should 

care for its removal and transportation. 

The 11.8 tons of nonfermentable sugars are largely xylose. Pilotplant experiments on the growing of fodder yeast on these sugars are in 

progress and show some promise. This material may prove to be a very undesirable source of stream pollution if it is not used. 

Other Plants 

There has been a great deal of interest in the possibility of producing alcohol from smaller quantities of wood waste, and for this reason the 

effect of plant size on production costs should be considered. The cost of 

the acid, lime, steam, wood waste, water, and power may differ in various 

parts of the country because of variations in distance from the point of 

production. In general, however, these variations will be small and will 

depend on the amount processed. That charge may be assumed to be fixed. 

The costs for labor and plant will differ, depending on the size of the 

plant, Labor required for a wood-hydrolysis plant depends on the number of 

operations to be performed rather than on the size of the equipment, and, 

therefore, is practically independent of size. In a plant producing onefourth the amount of alcohol, the cost for labor would be approximately 

four times as much per gallon of alcohol produced, 

It is possible that a plant built under peacetime conditions would 

cost less, and also that many of the simplifications found in the pilotplant operations may result in a reduction in the cost of the equipment 

required but, in general, reduction in size does not result in a proportionate reduction in the cost of the equipment. 

At present it is not possible to forecast the postwar price of alcohol. 

Assuming, however, that the cost of production is similar to that under 

prewar conditions, alcohol must be produced for 30 cents per gallon or less 

in order to compete with other sources. Under such conditions, a plant 

processing appoximately 150 tons of wood waste daily would be about the 

smallest plant that could operate with a profit unless valuable uses could 

be found for the lignin. 

Conclusions 

A pilot-plant process has been developed for converting wood waste, 

consisting of chipped slabs and edgings, sawdust, and shavings, into ethyl 

alcohol by allowing dilute sulfuric acid at temperatures from 150° to 185° C. 

to flow continuously through a bed of the wood waste until the cellulose is 

hydrolyzed, neutralizing the excess acid continuously under pressure with 

lime, and fermenting the neutralized sugar solutions. 

Report No. R1617 -10-
The operating data from the pilot plant have been used to calculate 

the capacity and cost of operation of a commercial demonstration plant 

being constructed at Springfield, Oregon. 

Acknowledgment 

On behalf of the Forest Products Laboratory, the authors wish to 

express their appreciation to The Vulcan Copper and Supply Company, 

Cincinnati, Ohio, and The Bristol Company, Waterbury, Connecticut, for 

assistance in the installation and operation of the automatic control equip 

mentl 

Acknowledgment also is made to the following members of the Forest 

Products Laboratory staff: George J. Hajny, Martha L. Hannan, Sedgwick C. Rogers, and Ralph R. Marquardt for assistance in the fermentation experiments, and Janet L. Bubl. Mary N. Mitchell, and Albert A. Kline for the 

analytical determinations. 

Valuable assistance was received from the pacific Northwest Forest 

Experiment Station, Portland, Oregon, in obtaining represontative samples 

of Douglas-fir mill waste, 

Report No. R1617 -11-
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1. 

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3. 

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Report No. R1617 -12-
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Report No. R1617 -13-
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patent No. 799,358 (1936). 

28. 

Wood Saccharification, Rund. Deut. Technik. , March 24, 1938. 

29. and FINK, H. 

Scholler-Tornesch process. Tech. Bur. of Percola. March 1, 1939. 

30. 

Saccharification of wood. Chim. Ind. Agric. Biologia 15:195 (1939). 

31. 

U. S. Patents: 1,641,771; 1,890,304; 1,990,097; 2,083,347; 2,083,348; 

2,086,963; 2,088,977; 2,108,567; 2,123,211; 2,123,212; 2,188,192; 

2,188,193. 

32. STEYNE, A. N. 

Further notes on the Scholler-Tornesch process for the manufacture of 

alcohol from sawdust. Hamburg, Germany, Amer. consulate general, 

February 11, 1933. 

33. U. S. DEPARTMENT OF AGRICULTURE, 

Bulletin 983, Manufacture of ethyl alcohol from wood waste (1922). 

Report No. R1617 -14-
Table 1.--Composition and products from Douglas-fir sawmill waste 

Table 3 .--Continuous hydrolssie of a charge of Douglas-fir wood waste, using oontinuous addition of the 

dilute acid and continuous removal of the sugar solution 

Z M 67012 F 
Table 4.--Hydrolysis of Douglas-fir sawmill wood waste, using batch addition of first charge followed by continuous 

introduction of acid and continuous removal of sugar solution 

Z M 67013 F 
Figure 1.--Equipment for saccharification of wood and fermentation of 

wood sugar solutions. 

Z M 60753 F 
Figure 2.--Equipment for neutralization of wood sugars.