74 HATCH EXPERIMENT STATION. [Jan. 



driven over are replaced by a like quantity of dilute acid 

 by means of an "open-top'" separatory funnel, the flask 

 agitated to wash down the particles adhering to the sides, 

 and the process continued until the distillate amounts to 

 360 c.c.i 



The completed distillate is filtered to remove insoluble 

 fats into a 25-ounce lipped beaker, graduated at 500 c.c, 

 and 50 c.c. of phloroglucol solution gradually added, pre- 

 cipitating the furfural as phloroglucid, and the mixture 

 thoroughly stirred. The solution is made up to 500 ^ c.c. 

 with 12 per cent, acid, and allowed to stand at least fifteen 

 hours. 



The amorphous black precipitate is filtered under pressure 

 into a tared Gooch through an asbestos felt, washed care- 

 fully, never allowing it to become dry, with 150 c.c. of 

 water, dried at 100° C to a constant figure, weighed in a 

 glass-stoppered bottle, and the increase reckoned as phloro- 

 glucid, from which furfural, pentosans, etc., can be calcu- 

 lated by the following formulfc : — 



1. Less than .300 Gram Phloroglucid. 



1. Furfural =z (weight of the lihloroglucid-]- .0052) x -5170 



2. Pentosansrr (weight of the phloroglucid -j- -0052) X -8935 



3. Pentose 1= (weiglit of the phloroglucid -|- .0052) X 1-0156 



2. More than .300 Gram Fhloroglueid. 



1. Furfural z= (weight of the phloroglucid -}- .0052) X -5180 



2. Pentosans r= (weight of the phloroglucid -|- -0052) X -8822 



3. Pentose = (weight of the phloroglucid + .0052) X 1-0025 



Krober has published very complete tables for calculating 

 the results, which will soon be reproduced by the Associa- 

 tion of Official Agricultural Chemists. 



(e) Digestihility of the Pentoftans. 

 The investigations of Giinther, De Chalmot, Flint, Mann, 

 Kriiger, Glaubitz, Krober and Tollens, Cross and Bevan,^ 



* Theoretically, the process should be continued as long as the distillate gives 

 a reaction with aniline acetate on filter paper, but 12 distillates are usually con- 

 sidered sufficient. 



* Tollens advises 400 c.c, but in this laboratory 500 c.c are preferred. 



* Loco citato. 



