This is calculated into magnesia.
~Potash and Soda.~--Weigh out .5 gram of the dried ore, and mix with an
equal quantity of ammonic chloride; and to the mixture add gradually 4
grams of calcium carbonate ("precipitated"). Introduce into a
platinum-crucible and cover loosely. Heat, at first, gently; and then at
a red heat for from forty to sixty minutes. Transfer to a porcelain
dish, and digest with 60 or 80 c.c. of water; warm and filter: to the
filtrate add ammonic carbonate and ammonia, and filter; evaporate the
filtrate to dryness, adding a few drops more of ammonic carbonate
towards the end; when dry, heat gently, and then raise the temperature
to a little below redness. Dissolve in a small quantity of water, add a
drop of ammonic carbonate, and filter through a small filter into a
weighed platinum dish. Evaporate, ignite gently, and weigh. The residue
contains the soda and potash of the mineral as chlorides.
To determine the proportion of potassium, dissolve this residue in a
little water, add platinum chloride in excess, evaporate to a paste,
extract with alcohol, decant through a small weighed filter, wash with
alcohol, and dry at 100° C. Weigh. The substance is potassium platinic
chloride (2KCl.PtCl_{4}). Its weight, multiplied by 0.1941, will give
the weight of potash (K_{2}O).
To find the proportion of soda, multiply the weight of the potassium
platinic chloride by 0.
Pages:
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757