26 
BULLETIN 983, U. S. DEPARTMENT OE AGRICULTURE. 
Brix juice with 57.34 grams per liter of dextrose: and in the same 
cook, fermentation Xo. 20. there was a 10.7° Brix juice, with 56.90 
grams per liter of dextrose. The whole question here seems to be one 
of the solubility of the sludge at the time the neutral juice is diluted 
before fermentation. Commercially no such variation would be 
obtained. Concentration of the neutral juice in an evaporator is 
unn ecessary, for the reason that a juice of proper concentration for 
fermentation is obtainable directly from the diffusion battery. 
As outlined previously, the variations in sugar data in the different 
fermentations seem to have been caused by the presence of sludge 
when the sample was taken. With the adoption of the method by 
which the clear neutral juice was siphoned from the sludge before 
sampling, these variations practically vanished. Cook Xo. 41. how- 
ever, affords two check sets of fermentable sugar data with wide 
variations, as shown in the following table: 
Cook 41. 
Fermentation No. 
Total sugar. ?S£J2? Fennenta- 
nientable. 
dry wood. 
efficiency. 
Alcohol yield. 
Per cent of 
dry wood. 
Gallons 
absolute, 
per ton. 
4 ::. :■> 32.95 
5 57.1S 
6 56.S0 
7 47.20 
S 45.46 
102. BG 
3.992 
12. 075 
B9.14 
6. 690 
20.235 
95.46 
6.399 
19.355 
101.06 
5.629 
17.026 
101. 90 
5.466 
16.533 
Fermentation Xo. 4 is evidently of no value. This was found to be 
true of most of the other cooks included in this fermentation, although 
no reason can at present be assigned for it. as the acidity and attenu- 
ation of the yeast seemed to be normal. Fermentations Xos. 5 and 
6. however, show an average of 56.99 per cent of sugars fermentable, 
and fermentations Xos. 7 and S an average of 46.33 per cent of sugars 
fermentable. Both fermentations show fairly good checks and 
apparently normal fermentation. 
The first of the above averages was chosen as the cook average, for, 
as will be shown later, that point is on the curve in the series in which 
cook Xo. 41 belongs and is, no doubt, the proper value. The reason 
for the second set of results is still unknown. It is to be regretted 
that lack of material prevented further fermentations on this cook, 
as the above is the only case in which a condition of this kind was 
noticed. 
The acidity of the yeast, neutral juice, and beer is expressed in 
degrees, each degree being the number of cubic centimeters of N/10 
alkali required for 20 c. c. of solution, phenolphtalein being used as an 
indicator. Another unit that is frequently used in this country is 
