_Microcosmic Salt_ dissolves oxide of copper in the flame of oxidation to a green bead, not so intensely colored as the borax bead. In the reduction flame the bead, if pretty well saturated, becomes dark-green while hot, and brownish-red when cool, opaque and enamel-like. If the oxide is so little that no reaction is visible, by the addition of some tin, the bead appears colorless while hot, and dark brownish-red and opaque when cold. _Carbonate of Soda_ dissolves oxide of copper in the oxidation flame upon platinum wire, to a clear, green bead, which loses its color when cooling, and becomes opaque. Upon charcoal, it is reduced to the metal, the soda is absorbed by the charcoal, and the metallic particles melt with sufficient heat to a grain. (_b._) _Silver_ (Ag).--This metal occurs in nature in the metallic state, and in combination with other metals, particularly with lead. It also occurs as the sulphide in several mines. It crystallizes in cubes and octahedrons; is of a pure white color, great lustre, is very malleable and ductile, and is softer than copper, but harder than gold. It is not oxidizable, neither at common temperatures nor at those which are considerably higher. It is soluble in dilute nitric acid, and in boiling concentrated sulphuric acid. ([chi].) _Protoxide of Silver_ (Ag^{2}O).--It is a black powder. It is converted by acids and ammonia into oxide and metal. ([beta].) _Oxide of Silver_ (AgO).--It is a greyish-brown or black powder, and is the base of the silver salts. With aqua ammonia, it is converted into the black, fulminating silver. ([gamma].) _Superoxide or Binoxide of Silver_ (AgO^{2}).--This oxide occurs in black needles or octahedral crystals of great metallic lustre. It is dissolved by the oxygen acids with the disengagement of oxygen gas. _Behavior before the Blowpipe._--When exposed to the flames of oxidation and reduction, the oxides of silver are instantly reduced to the metallic state. _Borax_ dissolves silver-oxides upon platinum wire in the oxidation flame but partially, while the other portion is reduced, the bead appearing opalescent after cooling, in correspondence to the degree of saturation. The bead becomes grey in the flame of reduction, the reduced silver melting to a grain, and the bead is rendered clear and colorless again. _Microcosmic Salt_ dissolves oxides of silver in the flame of oxidation upon platinum wire to a transparent yellowish bead, which presents, when much of the oxide is present, an opalescent appearance. In the flame of reduction, the reaction is analogous to that of borax. By fusion with carbonate of soda in the oxidation and reduction flames, the silver oxides are instantly reduced to metallic silver, which fuses into one or more grains.