118 METHODS OF ANALYSIS [Chap. 



66 GALACTAN.— TENTATIVE. 



Extract a convenient quantity of the substance, representing 2.5-3 grams of the 

 dry material, on a hardened filter with 5 successive portions of 10 cc. of ether, place 

 the extracted residue in a beaker, about 5.5 cm. in diameter and 7 cm. deep, together 

 with 60 cc. of nitric acid of 1.15 sp. gr., and evaporate the solution to exactly one 

 third its volume in a water bath at a temperature of 94°-96°C. After standing 24 

 hours, add 10 cc. of water to the precipitate, and allow it to stand another 24 hours. 

 The mucic acid has in the meantime crystallized, but it is mixed with considerable 

 material only partially oxidized by the nitric acid. Filter the solution through filter 

 paper, wash with 30 cc. of water to remove as much of the nitric acid as possible, 

 and replace the filter and contents in the beaker. Add 30 cc. of ammonium car- 

 bonate solution, consisting of 1 part ammonium carbonate, 19 parts water, and 1 

 part strong ammonium hydroxid, and heat the mixture on a water bath, at 80°C., 

 for 15 minutes, with constant stirring. The ammonium carbonate takes up the 

 mucic acid, forming soluble ammonium mucate. Wash the filter paper and con- 

 tents several times with hot water by decantation, passing the washings through a 

 filter paper, to which final' y transfer the material and thoroughly wash. Evapo- 

 rate the filtrate to dryness over a water bath, avoiding unnecessary heating which 

 causes decomposition, add 5 cc. of nitric acid of 1.15 sp. gr., stir thoroughly the 

 mi.xture and allow to stand for 30 minutes. The nitric acid decomposes the am- 

 monium mucate, precipitating the mucic acid; collect this on a tared filter or Gooch, 

 wash with 10-15 cc. of water, then with 60 cc. of alcohol, and a number of times 

 with ether, dry at the temperature of boiling water for 3 hours, and weigh. Mul- 

 tiply the weight of the mucic acid by 1.33, which gives galactose, and multiply this 

 product by 0.9 which gives galactan. 



CRUDE FIBER.-OFFICIAL. 



67 REAGENTS. 



(a) l.S5% sulphuric acid solution. — Exact strength, determined by titration. 



(b) 1.25% sodium hydroxid solution. — Exact strength, determined by titration. 



68 DETERMINATION. 



Extract a quantity of the substance, representing about 2 grams of the dry 

 material, with ordinary ether, or use the residus from the determination of the ether 

 extract. To this residue in a 500 cc. flask add 200 cc. of boiling 1.25% sulphuric 

 acid; connect the flask with an inverted condenser, the tube of which passes only a 

 short distance beyond the rubber stopper into the flask, or simply cover a tall coni- 

 cal flask, which is well suited for this determination, with a watch glass or short 

 stemmed funnel, boil at once and cont'nue boiling gently for 30 minutes. A blast 

 of air conducted nto the flask will serve to reduce the frothing of the liquid. Filter 

 through linen and wash with boiling water until the washings are no longer acid; 

 rinse the substance back into the flask with 200 cc. of boiling, 1.25% solution of 

 sodium hydroxid, free or nearly free from sodium carbonate boil at once, and con- 

 tinue boiling gently for 30 minutes as directed above for the treatment with acid, 

 filter at once rapidly, and wash with boiling water until the washings are neutral. 

 The last filtration may be performed upon a Gooch crucible, a linen filter, or a tared 

 filter paper. If a linen filter is used, rinse the crude fiber, after washing is completed, 

 into a flat-bottomed platinum dish by means of a jet of water; evaporate to dryness 

 on a steam bath, dry to constant weight at 110°C., weigh, incinerate completely, 

 and weigh again. The loss in weight is considered to be crude fiber. If a tared filter 



