20 



The pentose sugars, that is, those containing five atoms of carbon to 

 each molecule, are the chief products of hydrolysis, bo h with acid and 

 an alkali. They are recognized by the fact that when distilled with 

 hydrochloric acid they give rise to furfurol, which can be collected and 

 determined, and thus the actual quantities of these sugars, as well as 

 the bodies in the cornstalk from which they are derived, can be approx- 

 imately ascertained. 



FURFUROL CONTENT OF THE SAMPLES. 



It is of interest to know what quantities of pentose-yielding bodies 

 (xyian) are contained in the various samples. The furfurol determi- 

 nations gave the following results : 



Results for furfurol and xylan. 



SUGARS. 



The sugars which are formed by digestion with acid and alkali, fol- 

 lowed by an acid, have both the property of rotating polarized light 

 and of reducing an alkaline copper solution. In the absence of a bet- 

 ter method, it is customary to report the whole of the reducing sugar 

 as dextrose. This, at best, is only an approximation; but it is the only 

 method available until more definite knowledge is obtained respecting 

 the properties of the mixture of sugars in the products obtained. 



In the data which follow, the sugars removed by the alkali were not 

 directly determined. The total quantity of reducing sugars in the 

 sample, hydrolyzed by dilute sulphuric acid, was determined ; in another 

 portion, the matters removable by digestion with dilute alkali were 

 ascertained; and in the residue the remaining sugar-producing bodies 

 removed by digestion with dilute acid. Xylose and arabiuose, which 

 are the chief sugars produced by the above-described operations, have 

 reducing properties that are not greatly different from those of dex- 

 trose, and therefore when expressed in terms of dextrose a near 

 approximation to the true amount of -them is secured. The following 

 data give the copper-reducing properties of the several products: 



Copper-reducing properties. 



