A popular chemistry; . SILVER 169 upon the surface. The Pb oxidizes to PbO, and isabsorbed by the porous cupel. The mass, appearssoiled and tarnished, but the refiner keeps his eyeupon it as the process continues, watching eagerly,until at last there is a brilliant play of colors—in a Fig. in the Furnace. moment more the last film of oxide disappears, andthe brilliant surface of the pure silver lies gleamingat the bottom.* * See Malachi iii. 3. During the cooling of the cake of Ag, some veryremarkahle phenomona are observed. When a thin crust of metal hasformed upon the surface, the Ag be
A popular chemistry; . SILVER 169 upon the surface. The Pb oxidizes to PbO, and isabsorbed by the porous cupel. The mass, appearssoiled and tarnished, but the refiner keeps his eyeupon it as the process continues, watching eagerly,until at last there is a brilliant play of colors—in a Fig. in the Furnace. moment more the last film of oxide disappears, andthe brilliant surface of the pure silver lies gleamingat the bottom.* * See Malachi iii. 3. During the cooling of the cake of Ag, some veryremarkahle phenomona are observed. When a thin crust of metal hasformed upon the surface, the Ag beneath it assumes the appearance ofboiling, and the crust is forced up into hollow cones about an inch high,through which the melted Ag is thrown out with explosive violence, some ofit being splashed against the arch of the furnace, and some solidifying intomost fantastic tree-like forms several inches in height. This behavior ofAg has been shown to be due to its property of mechanically absorbing O,at a temperature above its melting-point, which it gives off as it approachesthe point of solidification, the escaping gas forcing up the crust of solid Agformed upon the surface. 170 IKOEGANIC CHEMISTEY. Properties.—Ag is the whitest of the metals. It ismalleable and ductile, and is of all
Size: 1772px × 1410px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade18, booksubjectchemistry, bookyear1887
