276 The Philippine Journal of Science is 



- Table VI. — Data on the molasses used in the laboratory experiments. 





°C. Percent. 







' 







38.1 

 21.6 

 61.6 

 0.2 



0.53 

 0.11 



































acidity increases at the expense of the alcohol. The cell count 

 at the end of sixteen hours is low in the samples that give a 

 low yield of alcohol. The alcohol content is dependent on the 

 number of cells. The alcohol content for the five cultures is 

 fairly constant. The difference can well be accounted for by 

 slight differences in the vigor of the yeast caused by its previous 

 experience in the stock-yeast solution. All had the same appear- 

 ance under the microscope and reacted identically in the wort, 

 which justifies the conclusion that they are the same. The 

 maximum yield of alcohol is not reached until the end of the 

 fourth day. The results recorded in Table VIII are for the 

 standard solutions made up of the same -concentrations of molas- 

 ses and sulphuric acid as for Table VII (2 grams per liter solu- 

 tion) with the addition of varying amounts of ammonium flu- 

 oride. Three of these were kept at an average temperature of 

 36° C, while the others were at room temperature (30° C.) 

 throughout the experiment. 



Ammonium salts increase the activity of yeast, while fluorides I5 

 are reputed to stimulate the yeast and prevent the growth of 

 bacteria and wild yeast. 



The data in Table VIII indicate that high temperatures result 

 in a loss of alcohol and also that greater action of bacteria takes 

 place. The beneficial action of ammonium fluoride is well 

 brought out in the higher yields from samples 5, 6, and 8, where 

 the larger amounts of this salt were added in comparison with 

 7, which had no salt, fermented slowly, and had a comparatively 

 low yield. The influence of the fluoride was evident in the free- 

 dom from bacteria of samples 5, 6, and 8, and in the presence 

 of many bacteria in 7 and somewhat less contamination in 4, 

 where only a small amount of the salt was added. The slow 

 fermentation is due to the small amount of nitrogen food pre- 

 sent. In Table VII, where larger amounts of ammonium salts 



u Backeland, L. H., Journ. Am. Chem. Soc. (1892), 14, 212. 



