in the oxidizing flame. Behaves in a similar manner to tantalic acid, but the glass requires a very large dose of the acid to render it opaque under an intermittent flame. With an increased amount of the acid, the glass is clear and yellow, while warm, but becomes on cooling turbid, and when quite cold is white. in the reducing flame. The glass obtained in the oxidizing flame and which has become opalescent on cooling, is rendered clear in the reducing flame. With a larger addition of the acid, it becomes dull, and of a bluish-grey color on cooling, and a still larger amount of renders it opaque and bluish grey. Behavior with Mic. Salt on Platinum wire in the oxidizing flame. Dissolves in large quantities to a clear colorless glass. in the reducing flame. If the acid be not present in too large a proportion, the glass remains unchanged. An additional amount of the acid renders it violet, and a still larger quantity affords a beautiful pure blue color, similar to that produced by tungstic acid. If to such a bead some sulphate of iron be added, the glass becomes blood-red. The addition of peroxide of iron renders the glass deep yellow while warm, the color becomes paler on cooling. * * * * * 27. Pelopic Acid, Pp^{2}O^{3}. Behavior with Borax on Platinum wire in the oxidizing flame. Behaves similarly to the preceding. in the reducing flame. A bead containing sufficient of the acid to render it spontaneously opaque on cooling, has a greyish color. Behavior with Mic. Salt on Platinum wire in the oxidizing flame. Dissolves even in large quantity to a colorless glass. in the reducing flame. With sufficient dose of the acid, the bead becomes brown with a violet tinge. This reaction is readily obtained upon charcoal. Sulphate of iron renders the bead blood-red. * * * * * 28. Oxide of Antimony, SbO^{3}. Behavior with Borax on Platinum wire in the oxidizing flame. Even when in large proportion, dissolves to a clear glass, which is yellow when warm, but almost entirely loses its color on cooling. On charcoal, the antimonious acid may be almost expelled, so that tin produces no further change. in the reducing flame. A bead, that has only been treated for a short time in the oxidizing flame, when submitted to the reducing flame becomes grey and turbid from the reduced antimony. This soon volatizes and the glass again becomes clear. The addition of tin renders the glass ash-grey or black, according to the amount of oxide it contains. Behavior with Mic. Salt on Platinum wire in the oxidizing flame. Dissolves with ebullition to a glass of a pale yellow color while warm. in the reducing flame.