646 EXPERIMENT STATION RECORD. 



The quantitative determiuatiou of the pentoses is accomplished by- 

 distilling the material containing pentosan with hydrochloric acid of 

 known strength, whereby farfurol (C:,H402) is generated from the pen- 

 toses which are first formed, with the elimination of water. This 

 furfiirol is changed to an insoluble form in which it can be weighed by 

 the addition of phenylhydraziu,^ or better, as the investigations of 

 Kriiger and Tollens have shown, by phloroglucin.- 



It has been found that most vegetable materials, after they hiive 

 passed the first stage of growth, and as soon as traces of lignification 

 ai)pear, invariably contain pentosan. This pentosan is j)artially dis- 

 solved by boiling with dilute sulphuric acid, and thus increases the 

 amount of the nitrogen-free extract.^ 



Whether monosaccharids of other composition or their mother sub- 

 stances, as tetrosan, heptosan, etc., occur in vegetable substances, is at 

 present not known. Furthermore, we have no positive information as 

 to whether the substances which yield furfurol on distillation are always 

 really arabinose or xylose, or whether, as Cross and Bevan^ believe, 

 other substances (furfuroses or furfurosans) yield a part of the furfurol. 



h'liamnose (OoHi^Os-f H2O) and rhamnosan. — In some materials as 

 Rubia tmctorunij buckthorn berries, and possibly oranges, a part of 

 the sugar may be rhamnose. There may also be a derivative of rhara- 

 nose, rhamnosan. 



NONCAUHOHYDHATP^ CONSTITUENTS OF THE NITROGEN-FREE EXTRACT. 



Organic acids. — Among the substances dissolved by the reagents of 

 the Weende method may be organic acids, such as oxalic, succinic, 

 malic, citric, acetic, glycollic, and lactic acids, in the form of salts solu- 

 ble in water, acids, and alkalies. 



Higher alcohols. — Other constituents of the nitrogen-free extract are 

 higher alcohols, which, although closely rehited to the carbohydrates, 

 do not always possess exactly their composition. These are mannit, 

 dulcit, sorbit, inosit, perseit, etc. JSome of these occur commonly. 

 Beans, for instance, contain inosit. 



Ligiiin sxhstanccs. — By the term "lignin" or "iucrusting substances" 

 is commonly understood those substances not cellulose or xylan (wood 

 gum, pentosan) which are de])Osited in and upon the liguifled cell walls. 

 The Weende method separates these substances for the most part with 

 the crude fiber, but a certain amount may be dissolved by the reagents 

 used and so fall in the nitrogen-free extract. 



As a result of analyses of crude fiber rich in lignin Henneberg, and 

 also Dietrich and Konig,^ concluded that lignin was rich in carbon, 



'Liudsey and Holland, Mass. State Sta. Rpt. 1894, p. 177. 

 2Ztschr. augew. Chem., 1896, pp. 33, 194. 



^ A resume of the work thus i'ar (lone ou the pentoses and pentosans is given in 

 Jour. Landw., 44 (1896), p. 171 (E. S. R., 8, p. 281). 

 ■I Chem. News, 70 (1894), p. 296. 

 sLandw. Vers. Stat., 13 (1870), p. 222 ; 16 (1873), p. 419. 



