286 



FOOD AND FOOD ADULTERANTS. 



EXTRACT OR TOTAL SOLIDS. 



This can also be obtained either directly, by weighing or measuring 

 a sample into an open dish, driving off the moisture at 100 C. until a 

 constant weight is obtained, or indirectly, by calculation from the spe- 

 cific gravity of the de-alcoliolized solution. For the direct estimation 

 a small quantity should be weighed out; 10 grams is quite sufficient, 

 and 5 grams gives still better results. This is allowed to run out into 

 a thin film on the bottom of a shallow dish having an area of several 

 square inches. In this shape it is very readily dried to a constant weight 

 at 100 C., while if a larger quantity is taken this becomes quite diffi- 

 cult, and it is necessary to use a higher temperature. 1 



In case the indirect method is used the per cent, of extract may be 

 obtained from one of the various tables in use or by dividing the differ- 

 ence between the specific gravity and 1.033 by ths factor 3.86. The 

 result obtained is the number of grams of solid matter in lOOcc. of the 

 beer, and must be divided by the specific gravity of the original beer to 

 get the exact per cent. 



ORIGINAL GRAVITY. 



The ''original gravity" of beer is the specific gravity of the wort 

 from which it was made, before fermentation. This is ascertained by 

 computation from data given by the alcoholic content and the malt ex- 

 tract contained in the de-alcoholized liquid. The specific gravity of 

 the alcoholic distillate (or the specific gravity of the alcohol evapo- 

 rated, if the indirect method is used) when subtracted from 1.000 gives 

 a number called the "spirit indication." The degrees of gravity lost 

 are then ascertained by reference to the tablegiven below. The degrees 

 found are added to the specific gravity of the de-alcoholized beer, and 

 the number thus obtained is the original gravity. 



The following table was calculated by Graham, Ilofmann, and Red- 

 wood from actual experiments on malt worts fermented under normal 

 conditions: 



1 The following duplicate determinations show very satisfactory agreement in the 

 results obtained by using a small quantity for drying: 



