386 ZINC, CADMIUM, LEAD, &c. 



these bodies in the metallic state, and, compara- 

 tively speaking, in a state of considerable purity. 

 4. When the last seven of these metals are held 

 in solution by an acid (particularly sulphuric, or 

 muriatic, when these acids form soluble salts 

 with the metallic oxide) if we introduce into the 

 solution a plate of zinc, the metal previously in 

 solution is thrown down in the metallic state, 

 while a corresponding portion of the zinc is dis- 

 solved in its place. A plate of cadmium intro- 

 duced into a solution of any of the six metals 

 placed after it in the title of this chapter, will 

 also throw it down in the metallic state, while a 

 corresponding portion of the cadmium enters 

 into solution. In like manner a plate of lead 

 will throw down any of the five metals after it 

 in the metallic state. A plate of tin will throw 

 down any of the four metals after it ; a plate of 

 bismuth, any of the three metals after it ; a plate 

 of copper either of the two metals after it 5 and 

 mercury will throw down silver in the metallic 

 state. 



But silver is incapable of throwing down any 

 of the other metals mentioned in the title of 

 this chapter, though it is itself thrown down by 

 them all. Mercury throws down silver, but 

 none of the others ; copper throws down mer- 

 cury and silver, but none of those that precede 

 it. The same remark applies to every particular 

 metal ; it throws down all those which are placed 



