250 METHODS OF ANALYSIS [Chap. 



9 DEGREE OF FERMENTATION.— TENTATIVE. 



Calculate the degree of fermentation by the following formula: 

 ^ 100 X 2A 



O 



in which 



D = degree of fermentation ; 



A = alcohol (grams per 100 cc); and 



O = extract of original wort. 



10 TOTAL ACIDS.— TENTATIVE. 



Proceed as directed under XVI, 25. Express the result as lactic acid, grams per 

 100 cc. One cc. of N/10 sodium hydroxid is equivalent to 0.0090 gram of lactic 

 acid. 



1 1 VOLATILE ACIDS.-TENTATIVE, 



Proceed as directed under XVI, 27. Express the result as acetic acid, grams 

 per 100 cc. 



12 REDUCING SUGARS.-TENTATIVE. 



Dilute 25 cc. of the carbon dioxid-free beer, measured at 20°C., with water to 

 100 cc. of the same temperature. Determine the reducing sugars in 25 cc. of this 

 solution, as directed under VIII, 42. Express the result as grams of anhydrous 

 maltose per 100 cc. of beer. 



1 3 DEXTRIN.— TENTATIVE. 



To 50 cc. of the carbon dioxid-free beer measured at 20°C., add 15 cc. of hydro- 

 chloric acid (sp. gr. 1.125), dilute to 200 cc, attach to a reflux condenser and keep 

 in a boiling water bath for 2 hours. Cool, nearly neutralize with sodium hydroxid 

 solution, complete to a volume of 250 cc, filter and determine dextrose as directed 

 under VIII, 52 or 54. From the number of grams of dextrose per 100 cc. of beer, 

 subtract 1.053 times the amount of maltose as found in 12 and multiply the re- 

 mainder by 0.9 to obtain the number of grams of dextrin per 100 cc. of beer. 



14 DIRECT POLARIZATION.— TENTATIVE. 



Read the polarization of the original sample in degrees Ventzke in a 200 mm. 

 tube at 20°C. If the beer is turbid, clarify by shaking with alumina cream, filter 

 and correct the reading for dilution. 



1 5 GLYCEROL.-TENTATIVE. 



Proceed as directed under XVI, 8. 



16 ASH.-OFFICIAL. 



Evaporate to dryness 25 cc. of the carbon dioxid-free sample, measured at 20°C., 

 and proceed as directed under VIII, 4. 



1 7 PHOSPHORIC ACID.-TENTATIVE. 



To 25 cc. of the carbon dioxid-free beer, measured at 20°C., add 20 cc. of 2% 

 calcium acetate solution, evaporate to dryness and ignite at low redness to a white 

 ash. Add 10-15 cc. of boiling nitric acid (1 to 9) and determine phosphoric acid 

 (P2O5) as directed under I, 9. 



