ETHYL ALCOHOL FROM WOOD WASTE. 



31 



A similar increase in formic acid is shown in the curve for series lb 

 on page 50. 



As no data were available in the literature on the decomposition 

 of pentoses under the conditions that obtained in these experiments, 

 a number of autoclave cooks were made in which both pure dextrose 

 and pure xylose in sulphuric-acid solutions were used. The solu- 

 tions were made in such a way that the concentrations of sugar 

 would be comparable to those obtained in the regular runs, and the 

 data from these cooks are given in the two following tables: 



Solution of 0.8 of a gram of xylose in 100 c. c. of 0.5 per cent sulphlric acid, heated to 112 pounds in 20 

 minutes. Held at 112 pounds for 15 minutes. 



Ijl. 



III. 



Original xylose grams 



Residual reducing sugars do. . 



Residual reducing sugars, per cent of original 



Acetic acid grams 



Formic acid do . . 



0. 4000 

 .2268 

 56.7 



None. 

 .0232 



0. 4000 

 .2044 

 51.15 



None. 

 .0280 



0. 4000 

 . 2056 

 51.4 



None. 

 .0280 



Solution of 4 grams of dextrose in 100 c. c. of 0.5 per cent sulphuric acid, heated to 112 pounds in 20 minutes. 

 I, held at 118 pounds for 15 minutes; II, held at 112 to 116 pounds for 15 minutes. 



I. 



II. 



1.000 



2.000 



1.072 



1.472 



.0046 



.0070 



.0926 



.0766 



III. 



Original dextrose -. grams. 



Residual reducing sugars ■. do . . . 



Acetic acid do. . . 



Formic acid do. . . 



In addition to the above two series, one cook was made on an 

 aqueous solution of dextrose instead of a sulphuric-acid solution and 

 with the following results : 



Aqueous solution of 4 grams of dextrose in 100 c. c. of solution, heated to 112 pounds in 20 minutes. Held 

 at 112 pounds for 15 minutes. Reducing sugar 0.1891 gr. cu.=0.09685X10X4=3.874 grams of dextrose 

 per 100 c. c. 



Acetic. 



Formic. 



Total. 



0. 70 c. c. 

 .70 c. c. 

 . 00406 g. 



0.25 c. c. 

 .25 c. c. 

 .0011 g. 



0.95 c. c. 

 .95 c. c. 





The above data confirm the experimental results obtained in cooks 

 in the series mentioned and are also extremely interesting, as it is 

 found that approximately 50 per cent of xylose was decomposed 

 under the conditions used, even in a solution containing only 0.8 of 

 a gram per 100 c. c. of 0.5 per cent sulphuric acid. Furthermore, 

 only formic acid is produced, with no acetic acid whatever. A dex- 

 trose solution having five times the concentration of dextrose showed 

 on an average 64 per cent of the original dextrose remaining; and, 

 although formic acid was the main constituent of the total volatile 

 acid, some acetic acid was formed. 



