ETHYL ALCOHOL FROM WOOD WASTE. 23 
show that the first two are not the same as d-glucose in reducing 
power. Browne says: 
The statement has been made that in a mixture of sugars the reducing power of the 
individual sugars is somewhat modified by the other members present. The writer 
has subjected this statement to a thorough test and can discover no such influence. 
However, no wide ranges of varying sugar concentrations were 
tried by Browne, and therefore this point was checked up at the Forest 
Products Laboratory with mixtures of arabinose, xylose, and d-glu- 
cose, and no modifying influence in mixtures was found at widely vary- 
ing concentrations. Since there is no mutual influence, it is possible 
to correct the analyses after fermentation, if desired, for the non- 
fermentable sugars may in most cases be regarded as pentoses such 
as xylose. As the ratio of the reduction factors of xylose and dex- 
trose, as found by Browne and corroborated by the work at the 
Forest Products Laboratory, was 0.983, no great error has been 
introduced, because the reducing power of xylose is so nearly that 
of dextrose. 
The main error due to sampling, other than unavoidable ones aris- 
ing from the sampling of large quantities of material, has been found 
and in a great measure Overcome. On the sugar and alcohol yield 
sheets it will be noticed that up to cook 43 it was necessary to discard 
one or more of the fermentations in many of the cooks, because of 
poor yields or abnormal fermentation efficiencies. The reasons for 
these discrepancies were apparent. After the sugar was extracted 
from the wood and the acid solution had been neutralized, the clari- 
fied, settled neutral juice was concentrated to a heavy sirup in vacuo 
and stored as such. In the different cooks, varying amounts of 
sludge were precipitated when the neutral juice was concentrated. 
This sludge consists mainly of calicum sulphate, some calcium acetate, 
and calcium formate, with possibly some crystallized sugar. When a 
fermentation was to be made, the heavy sirup was diluted with water 
to give a solution of about 12.5° Brix. Previous to cook No. 43, 
samples of the 12.5° Brix juice were taken for analysis along with the 
sludge remaining in the carboy before sterilization. After that time 
the samples were made up and allowed to stand all night; the clear 
juice was then siphoned out into a clean 5-gallon bottle and given two 
intermittent sterilizations. The sample for analysis and the final 
Brix reading were taken at the same time that the 240 c. c. sample 
was taken for making up the sprout mash. This apparently obviated 
all of the former difficulties, and but few fermentations were dis- 
carded after this scheme was inaugurated. In addition, the sugar 
data in each run were much more concordant. 
