SPECIFIC GRAVITY. 



Determine specific gravity of sample after removal of carbon dioxid by means of 

 the pycnometer, by a small, accurately graduated hydrometer, by a Westphal bal- 

 ance, or by a Westphal plummet on the analytical balance. Care should be taken 

 when using the hydrometer that the liquid is quickly raised to room temperature 

 without loss by evaporation, after filling and before weighing, to prevent condensa- 

 tion of moisture on the outside of the flask. 



A. Determine specific gravity at 15 C. 



B. Determine specific gravity at 20 C. 



Calculate apparent extract or balling of beer according to Schultz and Ostermann's 

 table, page 127, Bulletin 65; Ellion's table, page 132, Bulletin 65, and Balling's extract 

 table if available. 



Object: To determine errors introduced by use of different tables. 



ALCOHOL. 



A. Measure 100 cc of the liquid at 20 C. into a round-bottomed distillation flask, 

 add 50 cc of distilled water, and if the beer is markedly acid, 0.1 or 0.2 gram of pre- 

 cipitated calcium carbonate, connect with condenser and distil off 90 cc into an 

 accurately graduated 100 cc stopped flask, care being taken to prevent loss of alcohol 

 during the distillation. This is best accomplished by inserting a two-holed rubber 

 stopper in the mouth of the flask, through one hole of which passes an adapter which 

 is tightly fitted to the end of the condenser and through the other a small funnel 

 which is filled with glass beads kept moist by sprinkling water. Wash down the 

 beads several times during the distillation with a small quantity of water, thus saving 

 any alcohol which 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 spe- 

 cific gravity as directed under "Specific gravity," and obtain the corresponding per- 

 centage of alcohol by volume or grams per 100 cc from Squibb' s alcohol table (p. 121, 

 Bull. 65), or Baumhauer's tables, if at hand. Calculate the 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. When the original extract of the wort is known the alcohol content of the beer 

 can be calculated by the following formula: A = 0.42 (B x B 2 ) when A = alcohol, B t 

 the original extract of the wort, and B 2 the extract of the beer. 



C. Dealcoholize 100 cc of the beer in a porcelain dish on the water bath, make up 



r> 



to 100 cc and take the specific gravity, then A^g 1 when A = specific gravity of alco- 

 hol, Bj the specific gravity of beer, and B 2 the specific gravity of the dealcoholized 

 beer. 



D. Calculate the alcohol content from the reading of the Zeiss immersion refrac- 

 toineter on the distillate at a definite temperature. 



E. Calculate from the formula A = ( Bj B 2 ) -j- 15, when A = reading on immersion 

 refractometer, B t reading of beer, and B 2 reading of dealcoholized beer, and deter- 

 mine value for A from alcohol tables accompanying the instrument. 



Object: To determine most accurate method commensurate with rapidity* of deter- 

 mination. 



EXTRACT. 



A. Evaporate 25 cc of beer in a tared platinum dish to constant weight in a water 

 oven at 80 C. 



B. Calculate according to formula, sp=g+(l a) in which sp is the specific 

 gravity of the dealcoholized beer, g the specific gravity of the beer, and a the spe- 

 cific gravity of the distillate obtained in the determination of alcohol, and determine 

 value of sp from extract in beer wort tables, pages 127 and 132, Bulletin 65. 



C. Dilute the residue from the distillation of alcohol to original volume, take the 

 specific gravity, and determine value from tables as in paragraph B. 



D. Take immersion refractometer reading and calculate extract from tables in 

 grams per 100 cc. 



Object : To determine whether or not method (A) gives incorrect results because 

 of dehydration of maltose. 



EXTRACT AND SPECIFIC GRAVITY OF WORT. 



Various methods are employed to obtain these figures, all of which are based on 

 the amount of alcohol produced by the fermentation of a given quantity of sugar. 



[Cir. 33] 



