The colored bead becomes colorless. With a large amount of the oxide, this reaction is best obtained upon charcoal, and is facilitated by the addition of tin foil. Behavior with Mic. Salt on Platinum wire in the oxidizing flame. With a considerable quantity of oxide an amethyst color is obtained, but never so dark as in borax. With but little oxide a colorless bead is obtained, in which, however, the amethyst-color may be brought out by adding a little nitre. While the bead is kept fused, it froths and gives off bubbles of gas. in the reducing flame. The colored bead immediately loses its color, either on platinum wire or on charcoal. After the reduction the fluid bead remains still. * * * * * 5. Oxide of Iron, Fe^{2}O^{3}. Behavior with Borax on Platinum wire in the oxidizing flame. With a small proportion of oxide, the glass is of a yellow color, while warm, and colorless when cold; with a larger proportion, red, while warm, and yellow, when cold; and with a still larger amount, dark-red, while warm, and dark-yellow, when cold. in the reducing flame. Treated alone on platinum wire, the glass becomes of a bottle-green color (F^{3}O^{4}), and if touched with tin, it becomes of a pale sea-green. On charcoal with tin, it assumes at first a bottle-green color, which by continued blowing changes to a sea-green (FeO). Behavior with Mic. Salt on Platinum wire in the oxidizing flame. With a certain amount of oxide, the glass is of a yellowish-red color, which on cooling changes to yellow, then green, and finally becomes colorless. With a large addition of oxide, the color is, when warm, dark red, and passes, while cooling, into brownish-red, dark green, and finally brownish-red. During the cooling process, the colors change more rapidly than with borax. in the reducing flame. With a small proportion of oxide there is no reaction. With a larger amount the bead is red, while warm, and becomes on cooling successively yellow, green, and russet. With the addition of tin the glass becomes, during cooling, first green and then colorless. * * * * * 6. Oxide of Cobalt, CoO. Behavior with Borax on Platinum wire in the oxidizing flame: Colors the glass of an intense smalt blue both whilst hot and when cold. When much oxide is present, the color is so deep as to appear black. in the reducing flame: As in the oxidizing flame. Behavior with Mic. Salt on Platinum wire in the oxidizing flame. As with borax, but less intensively colored. During cooling the color becomes somewhat paler. in the reducing flame. As in the oxidizing flames. * * * * *