composition, 0.5300 plus or minus 0.0010 gm. shall be transferred
to a 150 ml. beaker and 25 ml. of 12N hydrochloric acid added.
The beaker and contents shall be heated on a steam bath for
30 minutes, stirred occasionally, and then filtered with the
aid of a tared, medium porosity, glass crucible and suction.
The beaker and contents of the crucible shall be washed with
a two-percent solution of hydrochloric acid and finally with
four 5 ml. portions of water. The crucible and residue shall
be dried in an oven maintained at 100 plus or minus 5 degrees
C. for one hour, cooled in a desiccator for 15 minutes, and
weighed. The loss in weight of the crucible and contents
shall be calculated to percentage of red phosphorus soluble
in 12N hydrochloric acid, The factor represented by the
letter E, given in the equation for calculating the percentage
of' antimony sulfide, shall be calculated as follows
F = percent solubility of the red phosphorus used in the
composition, expressed as a decimal fraction.
G = percent of volubility of the red phosphorus subtracted
from 100 and the result expressed as a decimal fraction.
220.127.116.11.1.2 In the course of analysis of samples of match
head composition, the volubility In hydrochloric acid of red
phosphorus shall be recorded whenever practicable.
18.104.22.168.2 Red phosphorus. - The residue obtained in
22.214.171.124.1 shall be transferred from the glass crucible to a
150 ml. glass beaker with the aid of a stirring rod and five
5 ml. porti. ons of 15N nitric acid. The crucible shall be
rinsed with four 5 ml. portions of distilled water, and the
rinsings caught in the beaker. The contents of the beaker
shall be heated on a steam bath for one hour and filtered
into the previously used crucible using suction. The beaker
and contents shall be washed with four 5 ml. portions of
distilled water. The crucible and residue shall be dried in
an oven maintained at 100 plus or minus 5 degrees C. for one
hour, cooled In a desiccator for one hour and weighed.
Percentage of red phosphorus In the sample shall be calculated