4C6 SCIENTIFIC RECREATIONS. 



amalgams are made with mercury, which is useful in various ways that will" 

 at once occur to the reader. 



SILVER is the whitest and most beautiful of metals, and its use for our 

 plate and ornaments is general. It is malleable and ductile, and the best 

 conductor of electricity and heat that we have. It is not unfrequently 

 met with in its native state, but more generally it is found in combination 

 with gold and mercury, or in lead, copper, and antimony ores. The mines 

 of Peru and Mexico, with other Western States pf America, are celebrated 

 Nevada, Colorado, and Utah in particular. The story of the silver mine 

 would be as interesting as any narrative ever printed. The slavery and the 

 death-roll would equal in horror and in its length the terrible records of war 

 or pestilence. We have no opportunity here to follow it, or its kindred 

 metals with which it unites, on the sentimental side ; but were the story of 

 silver production written in full, it would be most instructive. 



Silver is found with lead (galena), which is 

 then smelted. The lead is volatilized, and the 

 silver remains. It is also extracted by the 

 following process, wherein the silver and golden 

 ore is crushed and washed, and quicksilver, 

 salt, and sulphate of copper added, while heat 

 is applied to the mass. From tank to tank 

 the slime flows, and deposits the metals, which 

 are put into retorts and heated. The mercury 

 flies off ; the silver and gold remain in bars. 



In some countries, as in Saxony and South 

 America, recourse is had to another process, that 

 of amalgamation, which depends on the easy 

 Fig. 4 i 7 .-Native silver. solubility of silver and other metals in mercury. 



The ore, after being reduced to a fine powder, is mixed with common salt, 

 and roasted at a low red heat, whereby any sulphide of silver the ore may 

 contain is converted into chloride. The mixture is then placed, with some 

 water and iron filings, in a barrel which revolves round its axis, and the 

 whole agitated for some time, during which process the chloride of silver 

 becomes reduced to the metallic state. A portion of mercury is then 

 introduced, and the agitation continued. The mercury combines with the 

 silver, and the amalgam is then separated by washing. It is afterwards 

 pressed in woollen bags to free it from the greater part of the mercury, and 

 then heated, when the last trace of mercury volatilizes and leaves the silver 

 behind. 



Nitrate of Silver is obtained when metallic silver is dissolved in nitric 

 acid. It is known popularly as lunar caustic, and forms the base of 

 " marking inks." Chloride of silver is altered by light, but the iodide of 

 silver is even more rapidly acted on, and is employed in photography. 

 Fulminating silver is oxide of silver digested in ammonia. It is very dan- 



