394 BULLETIN OF THE BUSSEY INSTITUTION. 
whole of the mannan in the date stones and the ivory nut might 
eventually be hydrolized. 
On contrasting the percentage of furfurol obtained from the 
original date stones and ivory nut with the quantities of furfurol 
obtained from the residues left after dilute acids had been made to 
act on these materials, it will be seen that the residues retained a 
very large proportion of the original pentosans. In other words, 
it would seem as if the hydrolizing acids had acted first or at the 
least more readily upon the hexosan (paramannan) in the date 
stones and the ivory nut, than they did upon the xylan in these 
materials. 
As an example of the influence of time upon the action of the 
dilute acid, it may be mentioned that while one sample of the inner 
wood of the birch tree felled in May, on being boiled for one 
hour with hydrochloric acid of 1%, gave 12.49% of pentosans, a 
second sample, boiled in a similar way for an hour and a quarter, 
gave 13.70%. For that matter, there are numberless experiments 
on record which go to show how extremely liable to variation are 
the results of the hydrolysis of hemicelluloses by means of acids. 
As every agricultural chemist knows, the diverse results often ob- 
tained by the so-called Weende method of estimating cellulose 
illustrate the point sufliciently.* On the other hand, too long con- 
tinued action of the acid may sometimes diminish the yield of 
sugar. Haweyt and Winton ¢ have both shown by test experi- 
ments, that some dextrose may be destroyed by very long con- 
tinued boiling of it in presence of the acid by which it has been 
formed. As regards pentoses also, C. Schulze and Tollens § have 
found that the yield of sugar may be very much lessened if, in 
the process of hydrotizing a pentosan, the boiling should be too 
long continued or if too strong an acid be used. It is to be 
presumed, however, that in the foregoing experiments on the 
hydrolysis of woods, the action of the acid was seldom or never 
* Compare, for example, some of the instances cited by Reiss, Landwirth- 
schaftliche Jahrbiicher. 18. 743, 744. See also, Krauch, Versuchs-Stationen. 
24. 296. 25. 225, 226, and E. Schulze and Steiger, Versuchs-Stationen. 
36. 458. 
+ Cited in Hoffmann’s Jahresbericht. 1887, 30. 337. 
t Report of Connecticut Agricultural Experiment Station. 1887, p. 130. 
See also, E. Schulze, Zeitschrift fiir physiologische Chemie. 19, 51. 
§ Liebig’s Annalen der Chemie. 271, 59. 
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