98 



HATCH EXPERIMENT STATION. 



[Jan. 



few drops of aniline in a little 50 per cent, acetic acid). To 

 the completed distillate is gradually added a quantity of 

 phloroglucin * dissolved in 12 per cent, hydrochloric acid, 

 and the resulting mixture thoroughly stirred. The solution 

 first turns yellow, then green ; and very soon an amorphous 

 greenish precipitate appears, which grows rapidly darker, 

 till it finally becomes almost black. The solution is made 

 up to 500 c.c. with 12 per cent, hydrochloric acid, and 

 allowed to stand over night. In case there is very little 

 furfurol in the substance tested, and the resulting distillate 

 consequently small, it is best to add sufiicient 12 per cent, 

 h^^drochloric acid to the distillate before adding the phloro- 

 glucin solution, so that, upon the addition of the latter 

 solution, the resulting mixture will contain approximately 

 500 c.c. 



The amorphous black precipitate is filtered into a tared 

 Gooch crucible through an asl)estos felt, washed with 100 

 c.c. of water, dried to constant weight by heating three to 

 four hours at 100 degrees C, cooled and weighed, the in- 

 crease in weight being reckoned as phloroglucid. To calcu- 

 late the furfurol from the phloroglucid, f use the following 

 table : — 



Furfurol -5- by grammes substance taken X 1.84 = pentosans. 

 Furfurol -r- by grammes substance taken X 1.65 = xylan. 

 Furfurol -9- by grammes substance taken X 2.03 := araban. 



* Dissolve twice as much dry phloroglucin as furfurol expected in about 50 c.c. of 

 12 per cent, hydrochloric acid. Bring the hydrochloric acid into a water bath, and 

 stir thoroughly till the phloroglucin goes into solution. 



t The phloroglucid is a complex substance, of uncertain formula. It contains 63 

 to 64 per cent, of carbon and from 3.6 to 4.2 per cent, of hydrogen. The factors for 

 calculating the amount of furfurol from the phloroglucid were obtained after experi- 

 menting with known amounts of pure furfurol and phloroglucin. 



