ETHYL alcohol from wood waste. 27 



based upon the number of cubic centimeters of N/10 alkali required 

 to neutralize 10 c. c. of this solution and is, consequently, equivalent to 

 two of the above-mentioned degrees. In general, both the yeast and 

 the neutral-juice acidity increased about 4° during fermentation. 

 However, as outlined previously, the yeast was propagated in mo- 

 lasses which had not been sulphited, and in the course of several years 

 the acidity of the molasses increased about 15°. A microscopic 

 examination showed the presence of both bacteria and cocci, and the 

 increase in acidity was probably caused by both of these. Sometimes 

 the acidity increased during the fermentation almost double the 

 average amount without doing any apparent harm. 



RESULTS. 



The first series of digestion experiments was more or less pre- 

 liminary in character, as it was necessary to overcome a number of 

 technical difficulties growing out of unusual conditions that required 

 a combination of high pressure and high temperature in the presence 

 of an acid. It required further time to organize and coordinate the 

 work properly, especially in view of the fact that each successive run 

 or pair of runs represented different experimental conditions. The 

 fermentation equipment was not ready at the time; and, although 

 some fermentations were necessarily made, no great confidence was 

 placed in the value of the results. The total sugar data may be con- 

 sidered accurate, however, in view of the fact that confirmative runs 

 were made later, in which the necessary fermentations also were 

 carried out. 



The complete data for all the runs, beginning with No. 21, will be 

 found in the Appendix. These include the digester record, fermenta- 

 tion record, sugar and alcohol yields, and volatile-acid yields. An 

 analysis of the various results obtained is given under the different 

 subheadings that follow. 



EFFECT OF TEMPERATURE AND PRESSURE. 



The effects of various temperatures and pressures are grouped into 

 two classes — the first series, in which the ratio of water to wood was 

 400 per cent (four times as much water as dry wood) , the ratio recom- 

 mended by Simonsen; and the second series, in which the ratio of 

 water to wood was 125 per cent. In the first series the ratio of acid 

 to wood was 1.8 per cent, which was found by Simonsen to yield the 

 best results; and in the second series the ratio of acid to wood was 2.5 

 per cent. In addition, the first series was run with two time vari- 

 ables — first, a 15-minute cooking period, and, second, an instan- 

 taneous (0-minute) cook. The results are given in the following 

 tables and curves. 



