1903.] PUBLIC DOCUMENT — No. 33. 71 



with acetate of phenylhydrazine, dried and weighed the pre- 

 cipitate in glass tubes. This method was further studied 

 and improved by Flint/ Mann'^ and Tollens, and was desig- 

 nated the phenylhydrazine method. The Association of 

 OiBcial Agricultural Chemists adopted this method at its 

 meeting in 1895, and later it was slightly modified by 

 Krug.^ 



Hotter* rcconmiended that, in place of phenylhydrazine, a 

 portion of the furfural distillate be heated in closed glass 

 tubes with pyrogallol, and that from the weight of the re- 

 sulting precipitate be calculated the percentage of furfural. 



Counciler'' suggested that phloroglucol be employed in- 

 stead of the pyrogallol, for the reason that the union of the 

 furfural with the phloroglucol would take place at ordinary 

 temperature. Kriiger,^ Rimbach^ and Tollens studied and 

 perfected the method, and recommended it as reliable for 

 the determination of pentosans in coarse fodders, grains and 

 vegetables. The Association of Official Agricultm-al Chem- 

 ists adopted the phloroglucol method as recommended by 

 Ki'iiger and Tollens in 1897, as a provisional method with 

 slight modifications, the most important of which was the 

 use of the Gooch crucible in place of filter paper for collect- 

 ing the precipitate. Krober^ and Tollens have recently 

 published the results of a very exhaustive investigation of 

 the phloroglucol method, together with a complete table for 

 converting any weight of phloroglucid between .030 and 

 .300 gram into furfural, arabinose, araban, xylose, xylan, 

 pentose and pentosans. The principal conclusions were as 

 follows : — 



1. That the results are not influenced by the length of 

 time (over fifteen hours) the precipitate stands. 



2. That the phloroglucid is best collected in a Gooch 

 crucible. 



1 Berichte, 25, p. 2912; Lanclw. Vers. Stat., 42, p. 381. 



- Zeitsch. f. Angw. Chem. 1896, p. 33, 194. 



^ Bulletin 49, Division of Chemistry, U. S. Department of Agriculture. 



* Chemiker Zeitung, 1893, p. 1743. 



= Chemiker Zeitung, 1894, No. 51. 



« Zeitsch. fiir Angw. Chem., 1896, Heft 2. 



' Inaug. Diss. Gottingen, 1898. '^ 



» Journal f. Landw., 1900, p. 357 ; 1901, p. 7. 



