| Telluric Acid | Telluric Acid. --+--------------------------------------+-------------------------------- Opaque-red and reddish brown. --+--------------------------------------+-------------------------------- | Oxide of Copper | Oxide of Copper. --+--------------------------------------+-------------------------------- * * * * * TABLE II. Metallic Oxides 1. Oxide of Cerium, C^{2}O^{3}. Behavior with Borax on Platinum wire in the oxidizing flame. Dissolves into a red or dark yellow glass (similar to that produced by iron). During cooling, the color diminishes in the intensity and becomes finally yellow. If much oxide be dissolved, an opaque bead may be obtained with an intermittent flame, and a still larger quantity renders it opaque spontaneously. in the reducing flame. The color of the bead becomes paler, so that a bead, which is yellow in the oxidizing flame, is rendered colorless. With a large quantity of oxide the bead becomes white and crystalline on cooling. Behavior with Mic. Salt on Platinum wire in the oxidizing flame. As with borax. During the process of cooling the color entirely disappears. in the reducing flame. Both, when hot and cold, the bead is colorless, by which character oxide of cerium may be distinguished from oxide of iron. The glass remains clear even when containing a large quantity of the oxide. * * * * * 2. Oxide of Lanthanum, LaO. Behavior with Borax on Platinum wire in the oxidizing flame. Dissolves into a colorless glass, which, when sufficient oxide is present, may be rendered opaque with an intermittent flame, and becomes so spontaneously on cooling, when a still larger amount is dissolved. in the reducing flame. As in the oxidizing flame. Behavior with Mic. Salt on Platinum wire in the oxidizing flame. As with borax. in the reducing flame. No reaction. * * * * * 3. Oxide of Didymium, DO. Behavior with Borax on Platinum wire in the oxidizing flame: Dissolves to a clear dark amethystine glass. in the reducing flame. No reaction. Behavior with Mic. Salt on Platinum wire in the oxidizing flame. As with borax. in the reducing flame. No reaction. * * * * * 4. Oxide of Manganese, Mn^{2}O^{3}. Behavior with Borax on Platinum wire in the oxidizing flame. Affords an intense amethyst color, which on cooling becomes violet. A large quantity of the oxide produces an apparently black bead, which however, if pressed flat, is seen to be transparent. in the reducing flame.