Aluminum Silicate Hydrate with
Silicon Dioxide
Kasseki
Aluminum Silicate Hydrate with
Silicon Dioxide is a mineral substance, mainly composed of aluminum silicate
hydrate and silicon dioxide.
It is not the same substance
with the mineralogical talc.
Description:
Aluminum Silicate Hydrate with
Silicon Dioxide occurs as white to light red powdered crystalline masses, which
becomes easily fine powder on crushing. The powder is roughish and easily
adheres to skin, and becomes slightly darken and obtains plasticity when
moisten with water.
It has a characteristic odor
and almost tasteless. It feels like as sand of fine grains by chewing.
Under a microscope <5.01>, the powder of
Aluminum Silicate Hydrate with Silicon Dioxide, thoroughly grained between a
slide glass and a cover glass together with mounting medium, shows numbers of
round to polygonal crystals not smaller than 10 mm in diameter.
Identification:
To 0.5 g of powdered Aluminum
Silicate Hydrate with Silicon Dioxide add 3 mL of diluted sulfuric acid (1 in
3), heat until white vapors evolve, then after cooling add 20 mL of water, and
filter. The filtrate neutralized to be a weak acidity with ammonia TS responds
to the Qualitative Tests <1.09> (1), (2) and (4) for
aluminum salt.
Purity:
(1) Heavy metals. To 1.5 g of Aluminum Silicate Hydrate with
Silicon Dioxide add 50 mL of water and 5 mL of hydrochloric acid, and boil
gently for 20 minutes while thorough shaking. After cooling, centrifuge, and
separate the supernatant liquid. Wash the precipitate twice with 10 mL portions
of water, centrifuging each time, and combine the supernatant liquids. Add
ammonia solution (28) dropwise to the combined liquid until a slight
precipitate form, then add, while shaking vigorously, dilute hydrochloric acid
dropwise to dissolve the precipitate. Add 0.45 g of hydroxylammonium chloride
to this solution, heat, then after cooling add 0.45 g of sodium acetate
trihydrate and 6 mL of dilute acetic acid, and add water to make 150 mL. Perform
the test with 50 mL of this solution as the test solution. Prepare the control
solution by adding to 2.0 mL of Standard Lead Solution, 0.15 g of
hydroxylammonium chloride, 0.15 g of sodium acetate trihydrate and 2 mL of
dilute acetic acid, and add water to make 50 mL (not more than 40 ppm).
(2) Arsenic. To 1.0 g of Aluminum Silicate Hydrate with Silicon
Dioxide add 5 mL of dilute hydrochloric acid, heat gently until boiling begins
while shaking thoroughly, then cool quickly, and centrifuge. To the precipitate
add 5 mL of dilute hydrochloric acid, shake thoroughly, and centrifuge. Repeat
this operation with 10 mL of water, combine all extracts, and concentrate the
extract to make 5 mL by heating on a water bath. Perform the test using this
solution as the test solution (not more than 2 ppm).
Containers and storage:
Containers.Well-closed containers.
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