36 
BULLETIN 1187, U. S. DEPARTMENT OE AGRICULTURE. 
The combustion capsules are the same type as are used in coal 
analysis, have a capacity of 25 milliliters, are 20 millimeters high, 
and 40 millimeters in diameter. Ovens and crucibles for making 
ash determinations are pictured in Figure 30. 
ACIDITY IN FLOUR. 9 
To determine the acidity of flour, weigh 18 grams into a 500 cubic 
centimeter Erlenmeyer flask and add 200 cubic centimeters of dis- 
tilled water, previously freed from carbon dioxid by boiling. Place 
the loosely stoppered flask in a water bath kept at 40° C. for 10 
minutes, shaking repeatedly. Remove the flask and with an occa- 
sional shaking allow it to stand at room temperature for one hour. 
Fig. 28. — Bench showing analytical balances used for weighing small samples of grain, flour, etc., for 
the purpose of making ash, moisture, pretein, and other tests. 
Filter through a dry folded filter, rejecting the first 10 cubic centi- 
meters and receiving the succeeding 100 cubic centimeters in a 
graduated flask. Titrate the filtrate with N/20 sodium hydroxid, 
using 2 cubic centimeters of carefully neutralized phenolphthalein 
in alcohol as an indicator. Each cubic centimeter of N/20 sodium 
hydroxid represents 0.005 gram of lactic acid or 0.05 per cent acidity 
as such. 
PROTEIN IN WHEAT AND FLOUR. 
Reagents. — -N/10 hydrochloric acid; N/20 sodium hydroxide; 
concentrated sodium hydroxide (600 grams per liter) to which has 
9 Official and Tentative Methods of Analysis of the Association of the Official Agricultural Chemists, 
revised to November 1, 1919, p. 167. 
