XVI. METHODS FOR THE ANALYSIS OF VINEGAR. PROVISIONAL. 



1. Preparation of Sample. 



For microscopical examinations employ the original sample but for chemical 

 analysis filter if turbid. Keep the samples in glass-stoppered bottles and ana- 

 lyze promptly to avoid fermentation. 



2. Calculation of Results. 



Express all results as per cent by weight. For most purposes cubic centimeters 

 may be regarded as grams ; if greater accuracy is desired weigh or calculate 

 weight from specific gravity. 



3. Specific Gravity. 

 Determine as directed under " XIII. Wine," page 83. 



4. Alcohol. 



Carefully neutralize 100 cc and distil 40 cc ; redistil until 20 cc have passed 

 over ; cool to 15.5 C. and make up to 20 cc with distilled water. Determine the 

 specific gravity by means of a pycnometer and calculate the percentage by 

 weight from Table II, page 203. 



5. Solids. 



Evaporate 10 cc to a sirupy consistency on a water bath in a tared platinum 

 disi of 50 mm o.io;a>eter, dry for two and one-half hours in the drying oven at the 

 vemperature of boilmg water, cool, and weigh. 



- ; 6. Ash. 



Proceed as directed under " VI. General Methods," page 38, employing the 

 residue from the determination of the solids, according to the preceding section. 



7. Solubility and Alkalinity of the Ash. 



Ash 25 cc of the vinegar, extract the ash repeatedly with hot water on an 

 ashless filter, dry and ignite the filter with the undissolved residue, cool, weigh, 

 and calculate as insoluble ash. Titrate the aqueous extract with tenth-normal 

 acid, using methyl orange as indicator. 



8. Phosphoric Acid of the Ash. 



Determine in the water-soluble and water-insoluble portions by the official 



method, page 2, under " I. Fertilizers." Express the results as milligrams of 



phosphoric acid in 100 grams of vinegar. 



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