2 



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. 

 The amorphous black precipitate is filtered into a tared gooch through an 

 asbestos felt, washed with 100 c. c. of water, dried to constant weight by heat- 

 ing four hours at 100 C, cooled and weighed in a weighing bottle, the increase 

 in weight being reckoned as phloroglucid. To calculate the furfural from the 

 phloroglucid, use the following formulae : 



Phloroglucid (less than and up to 0.2 gram) -r- 1.82 = Furfural. 

 Phloroglucid (from 0.2 to 0.3 gram) -r- 1.895 = Furfural. 



Phloroglucid (from 0.3 to 0.4 grain) -h 1.92 = Furfural. 



Phloroglucid (from 0.4 gram) -=-1.93 = Furfural. 



To calculate the furfural to pentosan or pentose, use the following formulae : 

 I. (Furfural - 0.0104) X 1.68 = Xylan. 

 II. (Furfural -0.0104) X 2.07 = Araban. 



III. (Furfural 0.0104) X 1.88 = Pentosan. 



IV. (Furfural - 0.0104) X 1.91 = Xylose. 



V. (Furfural 0.0104) X 2.35=.Arabinose. 

 VI. (Furfural 0.0104) X 2. 13 = Pentose. 



QUALITATIVE TEST OF THE PURITY OF THE PHLOROGLUCOL. 



Dissolve a small quantity of the phloroglucol in a few drops of acetic anhydrid, 

 heat almost to boiling, and add a few drops of concentrated sulphuric acid. A 

 violet color indicates the presence of diresorcol. A phloroglucol which gives 

 more than a faint coloration must be purified by the following method : 



METHOD OF PURIFICATION OF PHLOROGLUCOL. 



About 300 c. c. of hydrochloric acid (specific gravity, 1.06) are heated in a 

 beaker, and 11 grams commercial phloroglucol added in small quantities at a 

 time, stirring constantly until it has almost entirely dissolved. Some impurities 

 may resist solution, but it is unnecessary to dissolve them. The hot solution is 

 poured into a sufficient quantity of the same hydrochloric acid (cold) to make 

 the volume 1,500 c. c. It is allowed to stand at least over night better several 

 days to allow the diresorcol to crystallize out, and filtered immediately before 

 using. The solution may turn yellow, but this does not interfere with its 

 usefulness. In using it the volume containing the required amount is added to 

 the distillate. 



METHOD FOR ESTIMATING GALACTAN. 



Extract 3 grams of the substance on a hardened filter with five successive 

 portions of 10 c. c. of ether, place the extracted residue into a beaker about 

 5.5 cm. in diameter and 7 cm. deep, together with 60 c. c. of nitric acid of 

 1.15 specific gravity, and evaporate the solution to exactly one-third its volume 

 on a water bath at a temperature of 94 to 96 C. After standing twenty-four 

 hours, add 10 c. c. of water to the precipitate, and allow it to stand another 

 twenty-four hours. The mucic acid has in the meantime crystallized, but is 

 mixed with considerable material only partially oxidized by the nitric acid. 

 The solution is therefore filtered through filter paper, washed with 30 c. c. of 

 water to remove as much of the nitric acid as possible, and the filter and contents 

 replaced in the beaker. Thirty c. c. of ammonium carbonate solution, consisting 

 of 1 part ammonium carbonate, 19 parts water, and 1 part strong ammonia, are 

 added, and the mixture heated on a water bath at 80 C. for fifteen minutes with 

 constant stirring. The ammonium carbonate takes up the mucic acid, forming 

 the soluble mucate of ammonia. The filter paper and contents are then washed 



