The residue is dissolved in hot water, diluted to about
50 c.c., and heated to boiling. About 2 grams (four times the quantity
of mixed metals present) of ammonium phosphate (AmH_{2}PO_{4}) are
weighed off, dissolved in the smallest possible quantity of water, and
boiled for a minute or two with a few c.c. of dilute sulphuric acid.
This is added to the boiling-hot solution of cobalt and nickel, which is
then treated cautiously with dilute ammonia until the precipitate
partially dissolves. The addition of the ammonia is continued drop by
drop with constant stirring, until the cobalt comes down as a pink
precipitate of ammonium cobalt phosphate (AmCoPO_{4}). The beaker is
placed on the top of a water bath with occasional stirring for five or
ten minutes. The blue liquid containing the nickel is decanted through a
small filter and the precipitate is dissolved with a few drops of dilute
sulphuric acid. The resulting solution is treated with a small excess of
ammonium phosphate and the cobalt again precipitated by the cautious
addition of ammonia exactly as before. The precipitate containing the
whole of the cobalt is filtered off and washed with small quantities of
hot water. The filtrate is added to the previous one containing the
greater part of the nickel.
The ammonium cobalt phosphate is dried, transferred to a platinum
crucible, and ignited over a Bunsen flame for fifteen or twenty minutes.
Pages:
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807