14 



with glass beads kept moist by sprinkling with water. Wash down the beads several 

 times during the distillation with a small quantity of water, thus saving any alcohol 

 that may have collected on the moist surface. Bring the contents of the receiver to 

 20 C. make up to the mark with distilled water, determine the specific gravity as 

 directed under specific gravity and obtain the corresponding percentage of alcohol 

 by volume and grams per 100 cc, from standard tables at 20 C. Calculate results 

 to per cent by weight by dividing the results expressed as grams per 100 cc by the 

 specific gravity of the original sample. 



(B) OPTIONAL METHOD 



Calculate the alcohol content from the reading of the Zeiss immersion refractom- 

 eter on the distillate, reporting the results at 20 C. 



4. EXTRACT. 



(A) Evaporate 25 cc of the beer in a tared platinum dish to constant weight in a 

 water oven at 80 C. 



(fi) OPTIONAL METHOD NO. 1. 



Calculate according to formula sp=g-\- (1 a), in which sp is the specific gravity 

 of the beer, a the specific gravity of the distillate obtained in the determination of 

 alcohol, and determine value of sp from standard extract of beer-wort tables. 



(c) OPTIONAL METHOD NO. 2. 



Take immersion refracto meter reading of dealcoholized beer and calculate extract 

 in grams per 100 cc. 



5. EXTRACT AND SPECIFIC GRAVITY OF ORIGINAL WORT. 



Calculate percentage of extract from the f ormula O = 2A -}- E, when O= original 

 extract of wort, A = alcohol by weight, and E = extract of dealcoholized beer. From 

 extract calculated as above compute from standard tables the specific gravity of the 

 wort. 



6. DEGREE OF FERMENTATION. 



Calculate from the formula D = _ in which D is the degree of fermentation 



r> 



A = percentage of alcohol by weight, and B the original extract. 



7. TOTAL ACIDS. 



(A) Heat 20 cc of the sample to incipient boiling to liberate carbon dioxid, and, 

 titrate with decinormal sodium hydroxid, using neutral litmus as indicator. Each 

 cubic centimeter of decinormal alkali employed is equivalent to 0.009 grams of lac- 

 tic acid. The number of cubic centimeters of decinormal alkali employed in titra- 

 ting 20 cc of beer is multiplied by 0.045 for the acidity expressed as grams of lactic 

 acid per 100 cc. 



(B) Calculate the cubic centimeters of decinormal sodium hydroxid required to 

 neutralize the acidity of 100 cc of the sample. 



8. VOLATILE ACIDS. 



(A) The volatile acid, as acetic acid, is determined by titrating 20 cc of the alco- 

 holic distillate with decinormal sodium hydroxid solution, using phenolphthalein as an 

 indicator. The number of cubic centimeters of decinormal alkali employed multi- 

 plied by 0.030 gives the acidity expressed as grams of acetic acid per 100 cc. 



(B) Calculate the cubic centimeters of decinormal sodium hydroxid required to 

 neutralize the acidity of 100 cc of sample. 



9. REDUCING SUGARS. 



Twenty-five cc of beer, free from carbon dioxid, is diluted with water to 100 cc. 

 The reducing sugar is determined in 25 cc of this solution, as directed on page 49 of 

 Bulletin 65, the solution being boiled four minutes instead of two. Express the 

 results in terms of maltose equivalent to copper reduced, according to Table IX, page 

 144, Bulletin 65. 



[Cir. 83] 



