Calvin P. Midgley
College Chicago, Illinois
Mundelein
I
Sodium Silicate Bead Tern in Qualitative Analysis
Accurate and informative bead tests, without borax, platinum needle, or heat, that make use of the ordinary ionic solutions of qualitative analysis and produce a permanent record are easily and rapidly performed with sodium silicate. A drop of concentrated water glass for each test to be run is allowed to fall upon a selected place on white paper. On top of each of these crystal clear liquid beads is placed, in order, a drop of an ionic solution to be tested. Surprisingly the watery liquid clings to the smooth surface of the bead; it does not run off to the paper. A round toothpick is now used to puncture the crust of the bead through the ionic solution and to mix the latter with the liquid center of the bead. An immediate change to a characteristic
color is noted for the following ions: Cr'+ Mn2+ FeS+ Fe'+ Co'+ Ni" Cu2+ HgC HgP+
gray-green pink-yellow-beige red-orange pale grsy dark blue pale green
squamarine blue or turquoise brown turning to black no change
Allowed to dry, the paper contains a permanent record of firmly attached solid beads. It should be noted that except for Hg+, all of the metals whose ions produce positive head tests occupy a place together in the periodic table.
Volume 44, Number 8, August 1967
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