EXPERIMENTAL M1LLIX0 aXD BAK1N 43 
CRUDE FAT. 
Wash any of the commercial brands of ether with 2 or 3 succes- 
sive portions of water, add solid sodium or potassium hydroxid, and 
let stand until most of the water has been abstracted from the ether. 
Decant into a dry bottle, add small pieces of carefully cleaned metal- 
lic sodium, and let stand until there is no further evolution of hydro- 
gen gas. Keep the ether, thus dehydrated, over metallic sodium 
in lightly stoppered bottles. 
Large quantities of soluble carbohydrates may interfere with the 
complete extraction of the fat. In such cases extract with water 
before proceeding with the determination. Extract about 2 grams 
of material with the anhydrous ether for 16 hours. Dry the extract 
at the temperature of boiling water for 30 minutes, cool in a desic- 
cator, and weigh: continue, at 30 minute intervals, this alternate 
drying and weighing to constant weight. For most feeds a period of 
1 to 1.5 hours is required. 
GASOLINE COLOR VALUE IN FLOCR. 
Place 20 grams of the flour in a wide-mouthed, glass-stoppered 
120 cubic centimeters bottle and add 100 cubic centimeters of color- 
less gasoline. Stopper tightly and shake vigorously for 5 minutes. 
After standing 16 hours, shake again for a few seconds until the 
flour has been loosened from the bottom of the bottle and thoroughly 
mixed with the gasoline, then filter immediately on a dry 11 centi- 
meter paper into an Erlenmeyer flask, keeping the funnel covered 
with a watch gla^- to prevent evaporation. In order to secure a 
clear filtrate, a certain quantity of the flour should be allowed to pass 
over onto the paper and the first portion of the filtrate passed through 
a second time. It will be found convenient to fit the filter paper to 
the funnel by means of water. Dry thoroughly either by standing 
overnight in a well-ventilated place or by heating. 
Determine the color value of the clear gasoline solution in a 
Schreiner or similar colorimeter, using for comparison a 0.005 per 
cent potassium ehromate solution. This solution corresponds to a 
gasoline number of 1.0 and is conveniently prepared by diluting 10 
cubic centimeters of a 0.5 per cent solution to 1 liter. The colori- 
meter tube, containing the gasoline solution, should first be adjusted 
so as to read 50 millimeters, then the tube containing the standard 
ehromate solution raised or lowered until the shades of yellow in 
both tubes match. The reading of the ehromate solution, divided 
by the reading of the gasoline solution, gives the gasoline color value. 
The color value may be determined also in Nessler tubes, using for 
comparison potassium ehromate solutions of various dilutions pre- 
pared from a 0.5 per cent solution and filling the tubes in all c 
to the height of 50 millimeter-. 
The standard is based on the average intensity of a yellow color 
found in high-grade unbleached spring wheat flour. 
Usually the gasoline solution is a true yellow, but sometimes, 
especially in the case of clear flour, a slight brownish tint is discernible, 
although thi- is not sufficient to interfere seriously with the accuracy 
• ; - Official and Tentative Methods of Analysis of the Association of Official Agricultural Chemists. 
I to Xovember 1, 1919. P. ~i. 
-- Official and Tentative Methods of Analysis of the Association of Official Agricultural Chemist;-. Re- 
vised to Xovember 1, 1919. P. 171. 
