26 



BULLETIN 983, U. S. DEPARTMENT OF AGRICULTURE. 



Brix juice with 57.34 grams per liter of dextrose; and in the same 

 cook, fermentation No. 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 

 unnecessary, 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 No. 41, how- 

 ever, affords two check sets of fermentable sugar data with wide 

 variations, as shown in the following table: 



Cook 41. 





Total sugar, 

 per cent of 

 dry wood. 



Per cent 

 of total 

 sugars fer- 

 mentable. 



Fermenta- 

 tion 

 efficiency. 



Alcohol yield. 



Fermentation No. 



Per cent of 

 dry wood. 



Gallons 

 absolute, 

 per ton. 



4. 



23.09 



32. 95 



57.18 

 56.80 

 47.20 

 45.46 



102. 66 

 89.14 

 95.46 

 101. 06 

 101. 90 



3.992 



6.690 

 6.399 

 5.629 

 5.466 



12. 075 



5 



20. 235 



6 





19. 355 



7 1 



17. 026 



8 



16. 533 



1 





Fermentation No. 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 Nos. 5 and 

 6, however, show an average of 56.99 per cent of sugars fermentable, 

 and fermentations Nos. 7 and 8 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 No. 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 



