72 HATCH EXPERIMENT STATION. [Jan. 



3. That the precipitate should be washed with small quan- 

 tities of water, and should not be allowed to become dry 

 durino; the washing;, 



4. That the presence of diresorcol in the phloroglucol 

 does not affect the results. ^ 



5. That the precipitate be dried four hours in a water 

 bath, and that the Gooch crucible be kept in a glass bottle 

 during the drying, and be weighed in the glass-stoppered 

 bottle after cooling, in order to prevent the hydroscopic 

 phloroglucol from taking on water. 



The Association of Official Chemists at its 1902 meeting: 

 adopted Krober's formulse and tables for calculating the 

 results. 



While the phloroglucol method has been perfected, it can 

 still be regarded only as a conventional method. Further- 

 more, the fact must not be overlooked that other substances 

 besides pentosans yield furfural. Thus Tollens^ and his 

 earlier pupils have shown that glycuronic, euxanthic and 

 urochloi-alic acids yield furfural on distillation with hydro- 

 chloric acid, and Cross and Bevan^ have obtained furfural 

 from oxy cellulose. Widstoe^ and others^ have also shown 

 that methyl pentosans C^H'(CH)^0'* frequently accompany 

 the true pentosans, and upon distillation yield methyl fur- 

 fural C5H3(CH)302 -+- 2H20 and is likewise precipitated by 

 phloroglucol. Fraps^ finds that the hydrochloric acid dis- 

 tillate from hay yields on standing, besides furfural, a black 

 precipitate and other substances which are precipitated by 

 phloroglucol. These latter he termed furaloids. 



Cross and Bevan ' have applied the term furfuroids in place 

 of pentosans to all furfural-3'ielding substances. Tollens, 

 on the other hand, as well as Stone, ^ believe it preferable 

 to retain the old name. 



' This statement has been disputed by American chemists (see especially 

 Fraps, Bulletin No. 172, North Carolina Experiment Station). 

 ^ Loco citato. 

 3 Berichte, 27, p. 1061. 

 * Berichte, 33, p. 143. 



" Zeitsch. fiir Angw. Chem., 1902, Heft 20, p. 481. 

 " Am. Chem. Jour., 25, p. 501. 



' Chemical News, 1894; Anf. Cliem. Jour., 22, p. 634. 

 « Chemical News, 1895, p. 40. 



