164 METHODS OF ANALYSIS. 



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

 the finger. 



Determine copper reducing material as directed under " VI. General Methods," 

 section "8. Starch (a), Direct Acid Hydrolysis," page 53. 



12. Starch. 



Extract 4 grams of the finely pulverized material with ether and 10 per cent 

 alcohol, as described in the preceding section, and determine starch by the 

 diastase method, as directed under " VI. General Methods," on page 53. 



13. Crude Fiber. 



Determine as directed under " VI. General Methods," on page 5G, except that 

 the fiber is filtered and weighed on a. paper rather than on a gooch, since the 

 latter is liable to clog, rendering filtration impossible. 



14. Tannin. 

 (For cloves and allspice.) 



Extract 2 grams of material for twenty hours with absolute ether. Boil the 

 residue for two hours with 300 cc of water, cool, make up to 500 cc, and filter. 

 Measure 25 cc of this infusion into a flask of about 1,200 cc capacity, add 20 cc 

 of indigo solution and 750 cc of distilled water, and proceed as directed under 

 " XIII. Wine," page 88. 



Ten cubic centimeters of tenth-normal oxalic-acid solution are equivalent 

 to 0.06232 gram of quercitannic acid, or 0.008 gram of oxygen absorbed. 



15. Cold- Water Extract. 

 (For ginger.) 



Place 4 grams in a graduated 200 cc flask, add water to the mark, shake at 

 half-hour intervals during 8 hours and let stand 16 additional hours without 

 shaking. Filter and evaporate 50 cc to dryness in a flat-bottomed metal dish. 

 Dry to constant weight at 100 C. 



16. Total Sulphur. 



(For mustard.) 

 Determine as directed under " III. Inorganic Plant Constituents," page 23. 



MICROSCOPIC EXAMINATION. 



The microscope is the most valuable means of detecting adulterants of 

 vegetable origin In spices, as it usually discloses the particular adulterant 

 present, even when in small amount. The analyst who undertakes this work 

 should have a general knowledge of vegetable histology and microscopic manipu- 

 lation, and should be thoroughly familiar with the microscopic appear;ui< 

 of the spices and spice adulterants. He should have at his command the 



