MIL-DTL-3301D
W
Alkalinity as sodium hydroxide, percent by weight =
4.0 (A-B) N
W
Where: A = milliliters of H2S04 solution required for the titration of sample
B = milliliters of standard solution required for the blank
C = milliliters of NaOH solution required for the titration of sample
N = normality of the standard H2S04 or NaOH
W= weight of sample in grams
4.4.7 Insoluble matter in toluene.
4.4.7.1 Apparatus. The extraction apparatus shall consist of a heat resistant glass assay flask, a block tin
condensing coil with a nickel, copper or tin-plated metal cap, which fits securely around the rim of the
flask, and a glass siphon cup which is suspended under the condenser. This apparatus shall be suitable for
use with an electric hot plate or steam bath.
4.4.7.2 Procedure. An ordinary Whatman, or equal, paper filter thimble shall be dried and weighed.
Transfer a weighed portion of approximately 6 gm of the sample to the paper thimble. The paper thimble
and its contents are placed into the glass siphon cup which is then suspended under the condenser by a
fine wire bail. Add approximately 60 ml. of toluene to the paper thimble, allowing the excess solvent
to flow over into the flask. The flask shall be cautiously heated on a steam bath or electric hot plate just
enough to vaporize the solvent. Cold water shall be circulated through the condenser. The extraction shall
be discontinued when the toluene drops colorless from the siphon cup. The extraction may be complete in
1 to 5 hours. When the solvent comes through clear, the paper filter shall be removed and washed
with a fine jet of toluene from a washing bottle to wash out any bitumen that may be retained at the top of
the paper and to break up any channels that may have been formed by the toluene passing through. If the
washings show any color, the thimble shall be put back into the siphon cup and the extraction continued
until the solvent again becomes colorless. The paper thimble shall then be removed, dried carefully to
constant weight at approximately 100 ºC (212 ºF) cooled and weighed. The solution in the flask shall be
rinsed into a weighed porcelain or silica evaporating dish and the solvent evaporated under a hood. The
residue shall be ignited over a flame or a muffle, the ash weighed, and the weight added to that of
insoluble matter in the filter thimbles. Calculate the corrected loss in weight of the original sample to
percent insoluble in toluene.
4.4.8 Ash. Transfer a weighed portion of approximately 1 gm. of the sample to a tared porcelain or
platinum crucible and place in a cold muffle furnace having a good air circulation and capable of having
its temperature regulated between 700 and 750 ºC (1292-1382 ºF). Gradually raise the temperature of the
furnace to a red heat. Finish the ignition to constant weight at a temperature between 700 and 750 ºC
(1292-1382 ºF). Cool in a desiccator and weigh. Calculate the weight of residue as percent ash in the
sample.
4.4.9 Manganese. Transfer approximately 10 grams of the compound to a tared crucible, weigh
accurately to 1 mg. and ignite at dull red heat until residue is free from carbon. Cool and dissolve in 10
ml. of concentrated nitric acid, and filter if necessary. Dilute to 100 ml. with distilled water and transfer a
20 ml. aliquot of the solution to a 250 ml. beaker. Add 1 gm. of lead peroxide and boil. Note if
manganese is present as indicated by the development of a red coloration in the solution. If the presence
of manganese is indicated, filter through asbestos and titrate the clean filtrate with N /10 oxalic acid until
the red coloration disappears. Calculate the percent manganese in the sample as follows:
percent manganese =
5.495 V N
7
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