CH. XIIl] QUANTITATIVE. 267 



chloric acid, and the distillate tested for furfurol (furfur- 

 aldehyde) by the colour reaction with aniline acetate. 



[Brown and Morris did not find pentoses in leaves of 

 Tropseolum: but compare the paper by De Chalmot, 

 Amer. Cham. J. xv. (1893).] 



Quantitative. 



It is not generally necessary to estimate dextrins, but ■ 

 if necessary the precipitate by alcohol may be estimated 

 by the method described for starch ; or it may be dissolved 

 in water, dried at 110°, and weighed as anhydrous dextrins. 



Estimation of glucoses, maltose, cane-sugar. 



For an account of the volumetric methods of estimating 

 the reducing power of solutions by Fehling's, Pavy-Feh- 

 ling's, or Sachsse's solutions, consult Sutton, Volumetric 

 Analysis, pp. 259 — 269, where full details are given for 

 preparing the standard solutions, and performing the 

 operations. 



[For standardising these solutions, pure anhydrous 

 glucose (dextrose) can now be obtained from dealers in 

 pure chemical reagents.] 



Divide the solution in which the sugars are to be 

 determined into three equal parts; 100 c.c. each is 

 generally convenient. 



(1) Use one part for the determination of the original 

 ' reducing power ' of the solution. 



(2) Use another part for the determination of the 

 ' reducing power ' after ' inversion ' with citric acid. 



(3) Use another part for the determination of the 



