1895.] 



PUBLIC DOCUMENT — No. 33. 



177 



acid of a certain strength. Their detection and estimation 

 depends upon the production and separation of furfurol, and 

 its subsequent precipitation with phenyl-hydrazin as furfurol 

 hydrazon. 



Method. 



Weigh out 3 to 5 grams (depending on the amount of 

 pentosans present) of the finely ground material, and trans- 

 fer to a 300 cubic centimeter flask. After addiu": 100 cubic 

 centimeters of hydrochloric acid of LOG specific gravity, con- 

 nect with a Liebig condenser, and distil 30 cubic centimeters, 

 taking ten to fifteen minutes for the distillation. Instead of 

 putting the flask in Rose's metal to difluse the heat, as Flint 

 and others suggest, we have placed it upon a piece of gauze 

 with equally satisfactory results. Now add 30 cu])ic centi- 

 meters more acid by means of a separatory funnel (the stem 

 of which passes through the cork into the flask), and so con- 

 tinue the process until a drop of the distillate gives no red 

 coloration on filter paper that has been moistened with ani- 

 line acetate (a few drops of aniline in a little 50 per cent, 

 acetic acid). Ten to eleven distillations are generally suffi- 

 cient. Flint has shown that for constant results the pres- 

 ence of a certain amount of salt in a definite quantity of 

 solution is essential. Furfurol hydrazon is more insoluble 

 with 81 grams of sodium chloride in 400 cubic centimeters 

 of distillate than when less is present, and these propor- 

 tions should be always used. Add to the obtained distillate, 

 brought into a 700 to 800 cubic centimeter beaker, the neces- 

 sary amount of salt and water to raise it to this standard (see 

 table following). 



