XXVI. COFFEES. 

 GREEN COFFEE. 



1 MACROSCOPIC EXAMINATION.-TENTATIVE. 



A macroscopic examination is usually sufficient to show the presence of excessiv ■ 

 amounts of black and blighted coffee beans, coffee hulls, stones and other foreign 

 matter. These can be separated by hand picking and determined gravimetrically. 



2 COLORING MATTERS.— TENTATIVE. 



Shake vigorously 100 grams or more of the sample with cold water or 70% alco- 

 hol by volume. Strain through a coarse sieve and allow to settle. Identify 

 soluble colors in the solution and insoluble pigments in the sediment as directed 

 under XI. 



ROASTED COFFEE. 



3 MACROSCOPIC EXAMINATION.-TENTATIVE. 



Artificial coffee beans are apparent from their exact regularity of form. Roasted 

 legumes and lumps of chicory, when present in whole roasted coffee, can be picked 

 out and identified microscopically. In the case of ground coffee sprinkle some of 

 the sample on cold water and stir lightly. Fragments of pure coffee, if not over- 

 roasted, will float, while fragments of chicory, legumes, cereals, etc., will sink imme- 

 diately, chicory coloring the water a decided brown. In all cases identify the par- 

 ticles that sink, by microscopical e.xamination. 



4 PREPARATION OF SAMPLE.— TENTATIVE. 



Grind the sample and pass through a sieve having holes 0.5 mm. in diameter 

 and preserve in a tightly stoppered bottle. 



5 MOISTURE.-TENTATIVE. 



Dry 5 grams of the simple at 105°-110°C. for 5 hours and subsequent periods of 

 an hour each until constant weight is obtained. The same procedure may be used, 

 drying in vacuo at the temperature of boiling water. In the case of whole coffee, 

 grind rapidly to a coarse powder and weigh at once portions for the determina- 

 tion without sifting and without unnecessary exposure to the air. 



SOLUBLE SOLIDS. 



6 Winion Method. — Tentative. 



Place 4 grams of the sample in a 200 cc. flask, add water to the mark and allow 

 the mass to infuse 8 hours, with occasional shaking; let stand 16 hours long r with- 

 out shaking, filter, evaporate 50 cc. of the filtrate to dryness in a flat-bottomed 

 dish, dry at 100°C. and weigh. 



7 ASH.-OFFICIAL. 

 Proceed as directed under VIII, 4. 



331 



