30 
BEXLETIX 983, U. S. DEPARTMENT OF AGEICULTTRE. 
long as decomposition does not become appreciable; but tlie following 
table ss on the decomposition of dextrose in sulphuric-acid solution 
shows a marked decomposition above 175 r C. 1 gram of dextr- 
in 25 c. c. of sulphuric acid of various concentrations heated for 30 
minutes at the indicated temperatures . 
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75.0 
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Xeunian calls 175 z C. the '"critical point" and claims that tech- 
nically there is no need of investigating the production of sugars at 
higher temperatures. The results of the work at the Forest Products 
Laboratory support this statement. 
Series II. however, shows that even though the total sugar yield 
decreased at temperatures higher than that corresponding to 7.5 
atmospheres, the portion of the total sugars which was fermentable 
increased sufficiently to balance the decrease in total sugars, and 
hence the final alcohol yield was practically the same at 7.5 and 9 
atmospheres. As outlined before, the necessity for complete data 
is at once apparent, and much of the value of series la and lb would 
be lost if the data for series II were not at hand. The increase, or 
rather, the percentage of increase, in fermentable sugars may be 
explained in part by the fact that there is a selective decomposition; 
that is. the pentose or reducing substances other than the hexose 
present are more easily decomposed at the high temperature than 
is the dextrose. The following table of volatile-acid yields shows 
that there was greater sugar decomposition, with consequent forma- 
tion of formic acid^ at 9 atmospheres than at 6 atmospheres. 
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