or THE 



. UNIVERSITY , Kn 



SPICES. \ or / 57 



FQ> 



treated for 24 additional hours with a fresh portion of alcohol, yielded, in their 

 experience, small additional amounts of extract. The method, however, gives nearly 

 the full amount of extract and the results are concordant; whereas, extraction in a 

 Soxhlet apparatus, if continued until no more extract is removed, is an interminable 

 operation, and, as it is difficult to keep the strength and temperature of the extract- 

 ing alcohol constant, gives results far from satisfactory. 



12. DETERMINATION OK COPPER-REDUCING MATTERS BY DIRECT INVERSION. a 



Extract 4 grams of the material on a Schleicher and Schuell's No. 589 blue-ribbon 

 washed filter, or some other filter that will completely retain the smallest starch 

 granules, with five successive portions of 10 cc of ether. After the ether has evap- 

 orated, wash with 150 cc of 10 per cent (by volume) alcohol. Weak alcohol is 

 employed instead of water, because, as pointed out by Lindsey, it is not so liable to 

 carry starch granules through the paper. 



Since it is not possible to wash samples of Batavia cassia with water or dilute alco- 

 hol, owing to the formation of a glutinous mass which clogs the filter, for the sake 

 of uniformity, all preliminary washing is best omitted in determinations made on all 

 varieties of cassia, as well as on cassia buds and cinnamon. 



Carefully wash the residue from the paper into a 500-cc flask, with 200 cc of 

 water, using a small wash bottle, and~gently rubbing the paper with the tip of the 

 finger. 



Convert the starch into dextrose by the Sachsse method, 1 ' as follows: 



Add 20 cc of 25 per cent hydrochloric acid (sp. gr. 1.125) and heat for three hours 

 on a boiling water bath. Cool the solution nearly, but not quite, neutralize with 

 sodium hydroxid solution, make up to 500 cc, and filter through a dry paper. 



Determine reducing matters by the Allihn method, as follows: 



Mix 30 cc of a solution containing 17:5 grams of Rochelle salts and 125 grains of 

 caustic potash in 500 cc of water, and .">0 cc of a solution of 34.69 grams of pure crystal- 

 lized copper sulphate in 500 cc of water, in a beaker of 200 cc capacity and heat to 

 boiling. To the boiling liquid, without delay, add 25 cc of the solution to be exam- 

 ined, and continue the heating until boiling logins again. After the reduced copper 

 suboxid has settled, collect on a < Jooch crucible, dry at a moderate heat, and finally 

 heat for three to five minutes at dull redness, taking care to avoid a bright red heat 

 and to allow access of sufficient air to complete the oxidation to copper ox id (after 

 Bartlett d ). After weighing, repeat the heating to make certain that the oxidation is 

 complete. 



From the weight of copper oxid calculate the weight of metallic copper, using the 

 factor 0.7986, and find the corresponding amount of dextrose in Table VIII. To 

 obtain the corresponding weight of starch, multiply the weight of dextrose by 0.9. 



If desired, the copper may be weighed as Cu. 2 O after washing with alcohol and 

 drying at 100 C., or it may be determined electrolytically by one of the official 

 methods. 



To prepare asbestos pulp for use in the Gooch crucible, cut woolly asbestos (best 

 quality) into small pieces, boil with hydrochloric acid, and wash free from acid and 

 tine particles on a sieve with one-mm meshes. Woolly asbestos of suitable quality, 

 when packed in the crucibles with the aid of a blunt glass rod, retains completely 

 the finely divided copper suboxid, which is not true of the variety usually employed 

 in filtering coarser precipitates. 



Copper-reducing matters by direct inversion was first determined in pepper by 



U. S. Drpt. of Atfr., Div. of Chrin., Bui. 13: p. 166. Conn. Agr. Expt. Sta. Kept., 1898, p. 187. Srr 



also Appendix, p. 1 .">!. 



b Chcin. < 'rut rail)!. 1S77, 8, T.\'l. 



Jour, prakl. Chcm.. ISSO. N. F., 22, .VJ. 



' Maine A.^r. Kxpt. Sta. lii-p;.. is.s.s, p. 207. 



