90 DEPARTMENT BULLETIN 1216, TJ. S. DEPT. OF AGRICULTURE 
condenses on the undersurface of the top, from which it drips upon the wad of 
absorbent cotton and then percolates through the sample. A complete extraction 
may be made in three hours. At the end of this time the apparatus is allowed 
to cool and the basket containing the extracted aggregate carefully removed. 
After thoroughly drying, the aggregate is placed upon a pan of the rough bal- 
ance and weighed. The difference between this weight and the original weight 
taken shows the amount of bitumen extracted, which is calculated upon a per- 
centage basis of the original. This figure should be corrected for fine mineral 
matter which passes through the meshes of the wire basket, as follows: The 
solution of extracted bitumen is thoroughly agitated and measured in a glass 
graduate. Five or ten cubic centimeters are then poured into a weighed plati- 
num crucible or dish, burned, and ignited to ash. The amount of mineral 
matter in the entire solution may then be calculated from the amount of ash 
produced from that portion ignited. The total percentage of such ash is then 
deducted from the percentage of bitumen already calculated in order to obtain 
the true percentage of bitumen. The amount of this correction will ordinarily 
vary from 0.1 per cent in uniformly coarse aggregates to 1 or 2 per cent in the 
analysis of aggregates containing a considerable amount of very fine mineral 
matter. 
SUGGESTED METHOD FOR EXAMINATION OF BITUMINOUS 
MORTARS 
8. Bituminous mortars may be extracted by the use of bronze tubes which 
are capable of being whirled in the type of centrifuge similar to the Babcock 
milk tester. This method is based on decantation of the supernatant solvent. 
(The sample shall consist of not less than 25 grams.) The difference between 
the amount of final aggregate and the original amount taken gives the amount 
of bitumen extracted, which is subject to correction by deducting the amount 
of ash determined from the washings. The ash correction shall be made as 
given under the centrifugal method. 
9. Mechanical analysis of the extracted aggregate shall be conducted in 
accordance with method No. 30. 
59. METHODS OF TESTING BITUMINOUS EMULSIONS 
(A. S. T. M. tentative standard method (5), serial designation D 244-26 T, except as 
indicated. See p. 1) 
1. For testing purposes emulsions shall be classified as follows : 
I. Emulsified light oils or liquid petroleum products intended for dust- 
laying purposes. 
II. Emulsified asphaltic materials the asphalt content of which is of a 
consistency suitable for construction or repair. 
( a i Containing little or no mineral matter. 
( b ) Containing appreciable quantities of mineral matter. 
METHOD FOR DETERxMINING MISCIBILITY OF BITUMINOUS 
EMULSIONS WITH WATER 
(Applicable to both Classes I and II) 
2. To about 50 cubic centimeters of the emulsion shall be gradually added 
about 150 cubic centimeters of distilled water, stirring the mixture while adding 
the water. The temperature is not important, but should be between 21 and 25° 
C. (70 and 79° F.). The mixture shall be allowed to stand for two hours and 
then examined for any appreciable separation. 
STONE COATING TEST 
(Applicable only to emulsions of Class II (a)) 
3. Four hundred and sixty-five grams of clean stone (one-fourth to three- 
fourths inch in size, not more than 5 per cent passing a one-fourth-inch screen 
and 100 per cent passing a three-fourth inch screen), see tentative specifica- 
tions for commercial sizes of broken stone and broken slag for highway con- 
