6 



all removed and the large flask is a little more than half full and the ammonia 

 distilled in the usual manner. If a sample be known to contain a considerable 

 amount of nitrate, use method p. 17 (c). 

 Page 54, first line, read pages "55-57," instead of page 55. 



METHODS FOR THE ANALYSIS OF FOODS AND FEEDING STUFFS. 



Page 62. Read caption in (c) DETERMINATION OF STARCH IN COMMERCIAL 

 STARCHES. 



Omit 3 in first line of (c) and insert 2.5. 

 Add after section (c), page 62, the following: 



(cj) DIASTASE METHOD FOR STARCH. 



Extract from 2 to 5 grams of the finely powdered substance with ether, bring 

 the extracted residue on to a filter, or into a G-ooch crucible, and wash with 

 150 cc of 10 per cent alcohol, and then with a little strong alcohol. Place the 

 residue in a beaker with 50 cc of water, immerse the beaker in a boiling water 

 bath, and stir constantly until all the starch is gelatinized, cool to 55, add 

 from 20 to 40 cc of malt extract and maintain at this temperature until the solu- 

 tion no longer gives the starch reaction with iodin : Cool and make up directly 

 to 250 cc, filter, bring 200 cc of the filtrate into a ten ounce flask with 20 cc of 

 25 per cent hydrochloric acid (sp. gr. 1.125), connect with a reflux condenser and 

 boil for two hours and a half, exactly neutralize while hot with sodium car- 

 bonate, avoiding excess, cool and make up to 500 cc. Mix the solution well, pour 

 through a dry filter, and determine the dextrose in an aliquot part by Allihn's 

 method, pages 52-57. Convert the\ starcn\inj-ojtlextroselby the factor .90. 



Add on page 62, after (c^, the following : 



(c 2 ) METHOD FOR ESTIMATING G-ALACTAN. 



Bring three grams of the substance into a beaker about 5.5 cm in diameter 

 and 7 cm deep, together with 60 cc of nitric acid of 1.15 specific gravity and 

 evaporate the solution to exactly one-third of its volume on a water bath at a 

 temperature of 94 to 96. After standing twenty-four hours, add 10 cc 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 cc of water, to remove as much of the 

 nitric acid as possible, and the filter and contents brought back into the beaker. 

 Thirty cc of ammonium carbonate solution consisting of one part ammonium 

 carbonate, 19 parts water, and 1 part strong ammonia, are added, and the beaker 

 brought onto a water bath and heated gently for fifteen minutes. The ammo- 

 nium carbonate takes up the mucic acid, forming the soluble muciate of ammo- 

 nia. The solution is filtered into a platinum or porcelain dish, and the residue 

 thoroughly washed with water to remove all of the muciate of ammonia. The 

 filtrate is evaporated to dryness over a water bath, 5 cc of nitric acid of 1.15 

 specific gravity are added, and the mixture thoroughly stirred and allowed 

 to stand for thirty minutes. The nitric acid decomposes the ammonium muci- 

 ate, precipitating the mucic acid, which is collected on a tared filter or Gooch 

 crucible, washed with from 10 to 15 cc of water, then with 60 cc of alcohol and 

 quite a number of times with ether, dried at 100 for a short time, and weighed. 

 The mucic acid multiplied by 1.33 gives galactose, and the product multiplied 

 by .9 gives galactan. 



