When in very large proportion dissolves to a clear glass, having a yellow tinge, while hot, which disappears on cooling, and when perfectly saturated, becomes milk-white. in the reducing flame. On charcoal the oxide is slowly and imperfectly reduced. The reduced metal forms the characteristic incrustation on the charcoal, but the is thin and does not exhibit its color clearly until quite cold. The addition of tin hastens the reaction. * * * * * 10. Oxide of Lead, PbO. Behavior with Borax on Platinum wire in the oxidizing flame. Dissolves readily to a clear yellow glass, which loses its color upon cooling, and when containing much oxide can be rendered dull under an intermittent flame. With a still larger addition of oxide it becomes opaline yellow on cooling. in the reducing flame. The plumbiferous glass spreads out on charcoal, becomes turbid, bubbles up, until the whole of the oxide is reduced, when it again becomes clear. It is, however, difficult to bring the lead together into a bead. Behavior with Mic. Salt on Platinum wire in the oxidizing flame. As with borax, but a larger addition of oxide, required to produce a yellow color in the warm bead. in the reducing flame. On charcoal the plumbiferous glass becomes grey and dull. With an over dose of oxide a part is volatilized and forms an incrustation on the charcoal beyond the bead. The addition of tin does not render the glass opaque, but somewhat more dull and grey than in its absence. * * * * * 11. Oxide of Tin, SnO^{2}. Behavior with Borax on Platinum wire in the oxidizing flame. In small quantity dissolves slowly into a clear colorless glass, which, when cold, remains clear, and cannot be rendered opaque with an intermittent flame. If a saturated bead, which has been allowed to cool, be reheated to incipient redness, it loses its rounded form and exhibits imperfect crystallization. in the reducing flame. A glass containing but little oxide undergoes no change. If much of the latter be present, a part may be reduced upon charcoal. Behavior with Mic. Salt on Platinum wire in the oxidizing flame. In small quantity dissolves very slowly to a colorless glass, which remains clear on cooling. in the reducing flame. The glass undergoes no change, either on charcoal or platinum wire. * * * * * 12. Oxide of Bismuth, BiO^{3}. Behavior with Borax on Platinum wire in the oxidizing flame.