xii, a. 6 Brill and Thurlow: Alcohol from Molasses 275 



a temperature of 65° C. is reached. Yeast heated for ten minutes 

 showed the effects of being subjected to this high temperature 

 even at the end of the second day. The cells had not become 

 so numerous as they were in the other cultures. A temperature 

 of 70° C. prolonged for ten minutes destroyed their powers, so 

 that they failed to propagate. Heating for longer intervals of 

 time at temperatures between 45° and 65° C. will seriously impair 

 their powers if it does not destroy them entirely, so that the 

 temperature of the fermenting liquid should be down to 40° C. 

 before the inoculating solution is added and should be rapidly 

 cooled to 30° C. 



Parallel tests of the five cultures of yeast isolated from fer- 

 menting nipa juice were made to determine if any difference 

 existed in the efficiency of these cultures. Two hundred grams 

 of molasses, of the quality shown by the data that follow, were 

 dissolved in water, 1 cubic centimeter of concentrated sulphuric 

 acid was added, and the whole was given a single heating. Sul- 

 phuric and hydrochloric acids have an inhibiting effect on the 

 growth of wild yeasts and bacteria ; consequently small quantities 

 of these are usually added. After sterilization the contents were 

 made up to 1 liter, 0.27 gram of ammonium sulphate was added, 

 and the solution was inoculated with 10 cubic centimeters" of 

 the inoculating solution. This will be called the standard solu- 

 tion for Table VI. The samples were run in duplicate at a tem- 

 perature of 30° C. They differed from each other in that the 

 second one of each yeast contained 0.06 gram of sodium fluoride 

 to the liter. The comparisons were made by removing 100 

 cubic centimeters of the ferment, adding 100 cubic centimeters 

 of water, and distilling exactly 100 cubic centimeters of the 

 mixture and determining the alcohol content by the use of the 

 Westphalt balance at 15.6° C. at the end of definite periods of 

 time. The acidity determinations were made by titrating 10 

 cubic centimeters of the ferment with 0.1 N alkali solution, using 

 phenolphthalein as an indicator. It is, therefore, expressed in 

 cubic centimeters of 0.1 N alkali necessary to neutralize 10 cubic 

 centimeters of the ferment. The alcoholic content is given in 

 percentage by volume. The cell count is comparative and is 

 the number of millions per cubic centimeter of ferment. In 

 Table VI the analysis of the molasses used throughout the labor- 

 atory experiments is given. 



The acidity of the ferment could not be determined with ex- 

 treme accuracy because of the dark color of the ferment and 

 the difficulty of observing color changes. The highest acidity 

 corresponds to the lowest alcohol content, showing that the 



