392 FOOD AND FOOD ADULTERANTS. 



III. Alcohol ia determined by distilling the beer. A picnometer of about 50cc. ca- 

 pacity ami with a graduated neck is used as a receiver. The picnometer is carefully 

 calibrated. Seventy-five cubic centimeters of beer are distilled until the distillate 

 reaches about the center of the scale on the neck of the picnometer. This is then 

 cooled to 15 C., dried, and weighed, and the alcohol determined by means of Bauni- 

 ber's table. 



9 



The percentage of alcohol by weight is to be given. In very acid beers it is neces- 

 sary to neutralize before distilling. 



IV. Original gravity of wort. This maybe ascertained, approximately, by doubling 

 the per cent, by weight of alcohol found as above, and adding the per cent, of extract. 

 As this procedure is not exact, it may be made more nearly so by using the formula 



100 (E + 2.0665 A) 

 100 + 1.0665 A 



V. Degree of fermentation. This is estimated by using the formula 



v,=ioo(.-f). 



VI. Sugar determination. This is to be determined directly, in the beer previously 

 freed from carbonic acid, by Soxhlet's method of weighing the reduced copper; 1.13 

 parts of copper correspond to 1 part anhydrous maltose. 



VII. Determination of dextrin is seldom required, and if required is to be per- 

 formed by Sachsse's method. 



VIII. Nitrogen. Twenty to thirty cubic centimeters are evaporated in a Hof- 

 meister " schalchen " or on warm mercury, and the extract burned with soda-lime. 

 The nitrogen may also be determined by Kjeldahl's method. 



IX. Acids. (a) Total acids: The carbonic acid is driven off from lOOcc. of beer by 

 heating in beakers for a short time to 40 C C. and the beer then titrated with baryta 

 water (one-fifth to one-tenth normal). The saturation point is reached when a drop 

 of the liquid has no longer any action on litmus paper. The acidity is to be given in 

 cubic centimeters normal alkali required for 100 grams beer and as grams per cent, of 

 lactic acid. The indication " acidity " or "degree of acidity " is insufficient. 



(fc) Normal beer contains but a very small quantity of acetic acid. The determina- 

 tion of fixed acid in the repeatedly evaporated extract is to be cast aside. The acetic 

 acid produced by souring of the beer is shown by the increase in total acids. A qual- 

 itative test of the presence of acetic acid in the distillate from beers containing acetic 

 acid is sufficient. Neutralized beer is to be acidified with phosphoric acid and dis- 

 tilled. Weigert's method is recommended. 



X. Ash. Thirty to fifty cubic centimeters of beer are evaporated in a large tared 

 platinum dish and the extract carefully burned. If the burning takes place slowly, 

 the ash constituents do not fuse together. 



XI. Phosphoric acid. This is to be determined in the ash obtained by evaporating 

 and burning in a muffle 50 to lOOcc. of beer to which not too much baric hydrate has 

 been added. The phosphoiic acid is determined in the nitric acid solution of the ash 

 by the molybdenum method. 



XII. Sulphuric acid. The direct determination is not permissible. The determi- 

 nation is to be made by using the ash prepared by burning with sodic hydrate and 

 potassic nitrate or baric hydrate and proceeding in the ordinary way. 



XIII. Chlorine. This is to be determined in the ash prepared with sodic hydrate. 



XIV. Glycerine. Three grams calcic hydrate are added to 50cc. of beer, evaporated 

 to a siropy consistence, about 10 grams coarse sea-sand or marble added, and dried. 

 The dry mass is rubbed up, put into a capsule of filter paper, placed in an extraction 

 apparatus, and extracted for six to eight hours with 50cc. alcohol. To the light col- 

 ored extract at least an equal volume of ether is added, and the solution, after stand- 



