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|  MIL-P-48239 (MU)
4.4.4.4.1 Aluminum. Transfer an accurately weighed
portion of approximately two grams of the sample to a
tared medium porosity sintered glass crucible. Extract
the sample with ten 25 ml portions of distilled water
at a temperature of 0 to 5C, using a filtering flask
and suction. Stir the contents of the crucible
with each portion of water for 1 minute before applying
suction. The sample shall be tested for complete
extraction by treating a few drops of the extracting
liquid on a white spot plate with a few drops of a 1
percent diphenylamine solution in concentrated sulfuric
acid. If a blue coloration develops, additional water
washings shall be used and retest made. Transfer the
extract quantitatively to a 400 ml beaker using
approximately 50 ml of wash water and reserve the
extract and washings for the barium nitrate determination.
Rinse the undissolved residue with alcohol and ether,
and aspirate until no further solvent odors are apparent.
Place the crucible and contents in a drying oven at 100
to 105C for 1 hour, cool in a desiccator and weigh.
Calculate the increase in weight of the crucible to
percent aluminum powder on a moisture free basis as
follows:
Percentage of aluminum powder
Wher :
A = increase in weight of filtering crucible
W = weight of sample
=
M
percent moisture expressed as a decimal fraction
4.4.4.4.2 Barium nitrate. To the extract reserved
during the aluminum powder determination, add 1 ml of
12N hydrochloric acid. Heat to boiling on a hot plate
and add slowly from a 50 ml pipette 50 ml of 3N (1:8)
sulfuric acid. Allow the mixture to boil gently for five
minutes and finally to digest for at least two hours
on a steam bath. Collect the precipitated barium sulfate
in a tared Gooch crucible which has been previosly heated
in a muffle furnace at approximately 750C for 30 minutes.
Wash the precipitate ten times with 25 ml portions of
10
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